I have found that writing some lines in CLAUDE.md makes Claude better than default.

A developer discovered that Claude's behavior could be improved by modifying the CLAUDE.md file, which dictates its actions. Initially, Claude exhibited undesirable behaviors like using the wrong package manager or running full test suites unnecessarily. The developer created five templates for CLAUDE.md based on client work, including Next.js, Python, monorepo, API service, and a lean starter, and made them available for free. It's also noted that Claude reads both the nearest and root CLAUDE.md files, allowing for separate workspace and package rules.