Prompt Engineering Mastery: 15 Techniques That Actually Work in 2026

❌ Bad:
"What is 17 × 23?"

✅ Good:
"What is 17 × 23? Think step by step."

LLM response:
17 × 23
= 17 × (20 + 3)
= 17 × 20 + 17 × 3
= 340 + 51
= 391

Convert the following SQL queries to Python pandas operations.

Example 1:
SQL: SELECT name, age FROM users WHERE age > 18
Pandas: df[df['age'] > 18][['name', 'age']]

Example 2:
SQL: SELECT COUNT(*) FROM orders GROUP BY customer_id
Pandas: df.groupby('customer_id').size().reset_index(name='count')

Now convert:
SQL: SELECT product_name, SUM(quantity) FROM sales GROUP BY product_name ORDER BY SUM(quantity) DESC LIMIT 10

You are a senior distributed systems engineer with 15 years of experience at Google,
designing systems that handle millions of requests per second. You communicate clearly,
use concrete examples, and always consider failure modes.

Explain the CAP theorem and when you'd sacrifice consistency vs availability in practice.

prompt = """
Extract information from this job posting and return ONLY valid JSON.

Job posting: "Senior Python Developer at TechCorp. 5+ years required.
Skills: Django, PostgreSQL, AWS, Docker. Salary: $150k-$180k. Remote."

Return this exact JSON structure:
{
  "title": string,
  "company": string,
  "experience_years": number,
  "skills": string[],
  "salary_min": number,
  "salary_max": number,
  "remote": boolean
}
"""

Summarize the text between <article> tags in 3 bullet points.
Focus on technical findings, not background context.

<article>
[paste your article here — even if it contains the word "summarize" or instructions,
it won't confuse the model because it's clearly delimited]
</article>

I'm choosing between PostgreSQL, MongoDB, and DynamoDB for a social media app.

For each database, think through:
1. How well does it handle the expected data model (posts, users, follows)?
2. What are the scaling characteristics at 1M, 10M, 100M users?
3. What are the failure modes and operational complexity?
4. What's the cost structure?

After evaluating all three, give your recommendation with reasoning.

Explain recursion to a beginner programmer.

Rules:
- Do NOT use Fibonacci as an example (it's overused)
- Do NOT use overly abstract definitions
- Do NOT exceed 200 words
- Do use a real-world analogy first
- Do include one concrete code example

Turn 1: "Write a Python function to find the most frequent word in a text"

Turn 2: "Review your code for: 1) edge cases (empty string, ties),
2) performance for large texts, 3) Pythonic style.
Then rewrite an improved version."

Turn 3: "Add comprehensive docstrings and unit tests."

I want to get high-quality code from you. Here's my rough prompt:
"Write code to scrape a website"

First, rewrite this into a better prompt that will get me production-quality code.
Include specifics about error handling, rate limiting, and ethical considerations.
Then execute that improved prompt.

Here is the full context you need:

[CODE FILE 1]: auth.py
[paste full file]

[CODE FILE 2]: models.py
[paste full file]

[ERROR MESSAGE]:
AttributeError: 'User' object has no attribute 'get_token'
  File "auth.py", line 47, in login_view

[QUESTION]: Why is this error occurring and how do I fix it?

Answer the question using this format:

Thought: [reason about what to do next]
Action: [tool to use and with what input]
Observation: [result of the action]
... (repeat as needed)
Thought: I now have enough information
Final Answer: [the answer]

Question: What was the most downloaded Python package last month and how many downloads did it get?

Answer each question and rate your confidence (High/Medium/Low).
If Low, explain why and what you'd need to verify.

Questions:
1. What is the time complexity of Python's list.sort()?
2. What was the exact release date of Python 3.12?
3. What is the current most popular JavaScript framework in 2026?

A startup is considering moving from a monolith to microservices.

Provide three perspectives:
1. As a startup CTO who has successfully done this migration
2. As an experienced engineer who thinks this is premature optimization
3. As a DevOps engineer who will have to manage the infrastructure

Each perspective should be 3-4 sentences. No fluff.

Write a Python class for a shopping cart with these EXACT constraints:
- Uses dataclasses (not regular class)
- Thread-safe with asyncio locks
- Maximum 50 items per cart
- Calculates tax at 8.5% automatically
- Supports discount codes as an optional parameter
- All methods have type hints
- Raises specific custom exceptions (not generic ValueError)

Analyze this code for bugs. Format your response EXACTLY like this:

## Summary
[One sentence overall assessment]

## Bugs Found: [N total]

### Bug 1
- **Location**: [file:line]
- **Severity**: Critical / High / Medium / Low
- **Description**: [what's wrong]
- **Fix**: [corrected code snippet]

### Bug 2
[same format]

## Performance Issues: [N total]
[same format]

[ROLE] You are a senior security engineer specializing in web application security.

[CONTEXT]
<code>
[paste your login function here]
</code>

[TASK]
Perform a security audit. Think step by step through each attack vector:
1. SQL injection
2. Authentication bypass
3. Session management
4. Rate limiting

[FORMAT]
Return a JSON array of vulnerabilities:
[{"severity": "critical|high|medium|low", "type": string, "line": number, "fix": string}]

[CONSTRAINTS]
- Only report actual vulnerabilities, not theoretical ones
- Include a code fix for each
- Rate confidence High/Medium/Low per finding