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Guides

Practical cheat sheets, one screen each — bookmark and come back, not a blog post you read once.

Prompts that work — Claude, ChatGPT and Gemini

Problem

You write a vague prompt ("do me an analysis of X") and it hands back something generic that you end up rewriting anyway.

Technique

Give the model: (1) a concrete role/context, (2) the exact output format you want, (3) 1–2 examples of what to do and what not to do. All three models respond better to structured instructions than to loose prose.

Example

Instead of "summarize this contract": "You're a lawyer reviewing this lease agreement. Give me a list of at most 5 risky clauses, each on one line: [clause] — [why it's risky] — [what to ask for instead]."

Common trap

Telling the model to 'be creative' AND 'be precise' in the same prompt without saying which one wins in case of conflict — the model guesses, and guesses differently every time.

Which model to use for which task? — decision matrix

Problem

You have access to several models and don't know which one to use for what — you end up always using the same one out of habit, not by judgment.

Technique

Ask yourself three things in order: (1) Is the data sensitive? → if yes, local first. (2) Is the task long-format/agentic code? → Claude Opus/GPT-5.3-Codex. (3) Do you need huge context (long documents)? → Gemini. Everything else (chat, summaries, short tasks) → the cheapest local model that handles it well.

Example

Reviewing a contract with a client's personal data: local model (never leaves your server). Large refactor of a repo: Claude Opus or GPT-5.3-Codex-Max. Summarizing a 300-page report: Gemini for the context window.

Common trap

Using the most expensive/powerful model for trivial tasks 'just in case' — most everyday tasks are handled just as well by an 8-27B local model.

How to run Qwen locally — hardware → first output

Problem

You want to try a local model but you don't know what hardware you need or where to start.

Technique

For Qwen3.6 27B (dense, the sweet spot right now): at minimum a 16-24GB VRAM GPU at Q4. Install llama.cpp or Ollama, download the quantized GGUF (Q4_K_M is the standard quality/size balance), run the local server, and point any OpenAI-compatible client at `http://127.0.0.1:8080/v1`.

Example

`ollama pull qwen3.6:27b` → `ollama run qwen3.6:27b "explain what RAG is in 3 lines"`. First output in minutes, not hours.

Common trap

Downloading the FP16/uncquantized version 'to get the best quality' and running out of VRAM — Q4_K_M loses very little real quality and runs on half the hardware.

OpenClaw vs Imaginclaw — quick reference

Problem

Both are chat gateways (WhatsApp/Telegram/etc.) to AI agents — which one do you pick and why?

Technique

The real question isn't 'which is better' but 'where do you want the model to live'. OpenClaw is open-source but BYO-API-key — by default your messages go through a third party's cloud (Claude/GPT/Gemini) even if the gateway runs on your machine. Imaginclaw runs on local models (Hera) by default, cloud only as an explicit fallback.

Example

If it matters to you that no message leaves your infrastructure (legal, health, client data): Imaginclaw or an OpenClaw configured exclusively with local Ollama. If you want frontier capability without running your own infrastructure: OpenClaw with Claude/GPT API.

Common trap

Assuming 'open-source' means 'sovereign' — OpenClaw is license-free, but the model running behind it by default is still a third-party API unless you configure it yourself to use only local models.

Sovereign AI vs cloud AI — when it matters where your data lives

Problem

It's not obvious when the difference between 'local' and 'cloud' is just a technical preference and when it's a real risk decision.

Technique

Ask yourself: if this conversation leaked tomorrow, who would it hurt? Third parties' personal data (clients, patients, employees), trade secrets, or anything with a legal obligation of confidentiality → local is the right answer, not a preference. For everything else, the cloud is simpler and usually enough.

Example

A law firm processing client case files: local, no debate (and in Colombia, with real implications under Law 1581 of 2012 on data protection). Writing a draft blog post: either one works.

Common trap

Treating 'local' as a synonym for 'secure' and nothing more — a poorly configured local model (port exposed to the internet, no auth) can be LESS secure than a well-managed commercial API. Local solves the problem of who you trust with your data, not whether your configuration is secure.

How to evaluate a model without believing the marketing

Problem

Every new release says 'outperforms X on benchmarks' — and almost never is that information useful for deciding whether it's worth it for you.

Technique

Ignore the vendor's benchmark. Build 5-10 REAL tasks from your own work (not generic ones), run them against the current model and the new one, and compare them blind. If you don't see a real difference on your tasks, don't migrate just for the benchmark number.

Example

Before migrating from one model to another for contract review: take 10 contracts already reviewed by a human, run both models, count how many real errors (not style ones) each one makes.

Common trap

Trusting a benchmark that the vendor itself chose to publish — almost nobody publishes the benchmarks where they lose.

AI vocabulary for builders (20 real terms)

Problem

AI jargon is full of terms that sound important but that nobody explains to you in a useful sentence.

Technique

20 terms, one line each: **Token** — the smallest unit of text a model processes (not exactly a word). **Context** — how much text the model can "see" at once. **Quantization (Q4/Q8)** — compressing a model so it uses less VRAM, with a small loss in quality. **VRAM** — the GPU's memory, the real bottleneck for running local models. **MoE (Mixture of Experts)** — a large model that only activates part of itself per token (faster than a dense model of the same total size). **Fine-tuning** — retraining a model with your own data. **RAG** — looking up real information before answering, instead of trusting what the model "remembers". **Agent** — a model that can use tools (search, run code, browse) in a loop, not just answer with text. **Hallucination** — the model invents a fact with total confidence. **Temperature** — how much randomness the response has (0 = deterministic, higher = more varied). **System prompt** — the invisible instruction that sets the model's behavior before your message. **Context window** — the total token limit (your prompt + the response) the model can handle in a turn. **Embedding** — turning text into numbers so it can be compared by similarity. **Zero-shot / few-shot** — asking for a task with no examples vs. with 1–2 examples in the prompt. **Open-weight** — the model's weights are downloadable (doesn't mean it's lightweight or easy to run). **API** — how your code talks to a model running on another server. **Latency** — how long it takes to respond. **Throughput** — how many requests it can handle in parallel. **Prompt injection** — an attack where malicious text inside the content the model processes makes it deviate from its instructions. **Guardrail** — a rule external to the model that blocks or corrects its output.

Example

This model has 262K of context — it can see ~200,000 words in one sitting, not that it's "smarter."

Common trap

Confusing context size with reasoning quality — they are two completely different axes; a model can have a huge context and still lose the thread in long texts ("lost in the middle").

Tokens, context window and limits — what they mean, when they affect you

Problem

The model "forgets" something you told it earlier in the same conversation, or cuts your response off mid-sentence.

Technique

Everything that goes in and out of a model is measured in tokens (approx. ¾ of a word in Spanish/English). The context window is a TOTAL shared limit across your prompt + the history + the response — they are not separate quotas. As you get close to the limit, the model starts losing detail on what came earlier.

Example

A model with 128K of context and a conversation with 100K tokens of history only has 28K free for your next message + the response — if you ask for a long document there, it will cut it off or over-summarize it.

Common trap

Pasting huge documents 'because the model has a lot of context' when you don't need to — more context isn't free: it costs more, takes longer, and the attention quality for each part drops the fuller it gets.

RAG vs fine-tuning vs prompting — when to use each one

Problem

You want the model to "know" something specific about your business and it's not obvious which of the three techniques to use.

Technique

**Prompting** (put the info directly in the prompt) — for small data that changes often, with no infrastructure. **RAG** (search and retrieve relevant info before answering) — for large knowledge bases that change frequently (documents, policies, catalogs). **Fine-tuning** (retrain the model) — only when you need to change the model's STYLE/behavior, not to add data — it's more expensive and not the right way to "teach it facts".

Example

A bot that answers about 500 products in a catalog that changes every week: RAG, not fine-tuning. A bot that must always respond in a specific legal tone regardless of the topic: there fine-tuning does make sense.

Common trap

Fine-tuning to make "the model know" specific facts — fine-tuning is not a reliable way to inject factual knowledge; the model can still hallucinate those same facts. For facts, use RAG.

Open-weight comparison — Qwen vs Kimi vs DeepSeek for whoever is going to run them

Problem

All three are "open-weight" but have completely different hardware requirements — the label does not tell you whether you can run them yourself.

Technique

Qwen3.6 27B dense: runs on 1-2 consumer GPUs (16-24GB VRAM at Q4) — the only one of the three truly accessible for individual self-hosting today. Kimi K3 (2.8T params) and DeepSeek V4 (up to 1.6T): open weights, but datacenter scale — hundreds of GB of VRAM even quantized, designed to be served via a provider's API or a private cluster, not on your desktop.

Example

If you have 1-2 GPUs and want to run something NOW: Qwen3.6 27B. If you want maximum open-weight capability and don't mind paying a provider to host it: Kimi K3 or DeepSeek V4 via API.

Common trap

Seeing "open weights, no restrictive commercial license" and assuming that means "I can run it on my machine" — open is about the license, not about the hardware it needs.