CLAUDE.md Best Practices: The Secret to Perfect AI Instructions

Problem: Claude Code forgets your project requirements between sessions and ignores your specific workflow preferences.

Quick Win: Create a CLAUDE.md file in your project root with this template:

# Project: Your App Name
 
## Context
Building a web application for task management with React and Node.js.
 
## Rules
- Always use TypeScript
- Follow React functional components only
- Use Tailwind CSS for styling
- Never modify package.json without asking
 
## Workflow
1. Analyze requirements first
2. Create tests before implementation
3. Show code diff before making changes
4. Commit with semantic messages

Claude Code treats CLAUDE.md as system rules, not suggestions. It's the difference between "please do this" and "you must do this."

Why CLAUDE.md Works

Claude Code has a strict adherence hierarchy:

• CLAUDE.md instructions: Immutable system rules that define project boundaries
• User prompts: Flexible requests that work within established rules

This means your CLAUDE.md becomes the foundation that persists across all conversations. User prompts provide parameters and direction, but CLAUDE.md defines the operational framework.

Behavioral differences you'll notice:

• CLAUDE.md steps followed sequentially vs user prompts adapted on-the-fly
• CLAUDE.md context maintained throughout entire session
• User prompts rarely override CLAUDE.md directives

Essential CLAUDE.md Structure

Break your CLAUDE.md into clear modules using markdown headers:

# Project Name
 
## Context
[What you're building and why]
 
## Technology Stack
- Frontend: React with TypeScript
- Backend: Node.js with Express
- Database: PostgreSQL
- Styling: Tailwind CSS
 
## Code Standards
- Use functional components
- Prefer const assertions
- Maximum 100 characters per line
- Always include JSDoc comments
 
## Forbidden Actions
- Never delete existing tests
- Don't modify .env files
- Avoid inline styles
- No direct DOM manipulation
 
## Workflow Process
1. Read existing code structure
2. Ask for clarification if requirements unclear
3. Show implementation plan before coding
4. Test changes before committing
5. Update documentation if needed

Advanced CLAUDE.md Techniques

File Access Control: Tell Claude exactly what files to read and avoid:

## File Reading Rules
### Allowed Files
- /src/components/*.tsx
- /src/hooks/*.ts
- /tests/*.test.ts
 
### Forbidden Files
- /node_modules/*
- /.git/*
- /build/*
- /dist/*

Context Front-loading: Provide examples upfront to prevent guesswork:

## Component Examples
### Button Component Pattern
```typescript
interface ButtonProps {
  variant: 'primary' | 'secondary';
  onClick: () => void;
  children: React.ReactNode;
}
 
export const Button: React.FC<ButtonProps> = ({ variant, onClick, children }) => {
  return (
    <button 
      className={`px-4 py-2 ${variant === 'primary' ? 'bg-blue-500' : 'bg-gray-500'}`}
      onClick={onClick}
    >
      {children}
    </button>
  );
};

This prevents context pollution from Claude reading random files and getting confused about your patterns.

Common Mistakes to Avoid

Mistake 1: Vague instructions like "write good code" Fix: Specific rules like "use React.FC type annotations for all components"

Mistake 2: Conflicting requirements in different sections
Fix: Review your CLAUDE.md for contradictions before saving

Mistake 3: Too many forbidden actions that block productivity Fix: Focus on critical constraints, not micro-management

Performance Considerations

Claude Code may warn about large CLAUDE.md files affecting performance. This is rarely a problem if you understand your token budget. Front-loading context in CLAUDE.md is more efficient than letting Claude randomly read files that might confuse it.

Token optimization strategy:

• Keep essential rules in CLAUDE.md
• Move detailed examples to separate reference files
• Link to context management techniques for large projects

Success Verification

You'll know your CLAUDE.md is working when:

• Claude follows your coding standards without reminders
• Project consistency improves across sessions
• Less time spent re-explaining requirements
• Claude proactively suggests improvements within your framework

Next Actions

1. Create your first CLAUDE.md using the template above
2. Test it by starting a new Claude Code session and asking for a simple feature
3. Refine your rules based on what Claude Code does or doesn't follow
4. Explore planning modes to combine with your CLAUDE.md setup
5. Learn terminal control techniques to maximize your CLAUDE.md effectiveness

Remember: CLAUDE.md isn't just documentation—it's your project's constitution. Every rule you write becomes law for Claude Code. Make them count.