One of the best ways to improve the results you get back from GitHub Copilot is by carefully defining your custom instructions. This helps the LLM to better understand your application, preferred technologies, coding guidelines, etc.. This information is shared with the LLM for every request, so you don’t have to provide all these details every time in your prompts.
But creating such a set of custom instructions can be a challenge. If you are looking for inspiration, here are some possible sources:
Awesome Copilot Instructions
Description: Contains a list of copilot instructions for different programming languages
Cursor Rules
Link: Free AI .cursorrules & .mdc Config Generator | Open Source Developer Tools
Description: Originally created for the Cursor IDE but also applicable when defining custom instructions for GitHub Copilot. No examples for .NET or CSharp but web frameworks are well represented.
Cursor Directory
Link: Cursor Directory
Description: Originally created for the Cursor IDE but also applicable when defining custom instructions for GitHub Copilot. The list of available examples is large. Especially web frameworks and technologies are well represented here.
A last tip
A last tip I found on the blog of Burke Holland is to add an extra instruction to avoid hallucinations and let the LLM ask you when it needs more context.
Avoid making assumptions. If you need additional context to accurately answer the user, ask the user for the missing information. Be specific about which context you need.
More information
Custom instructions when using GitHub Copilot
Adding repository custom instructions for GitHub Copilot - GitHub Docs
Free AI .cursorrules & .mdc Config Generator | Open Source Developer Tools
Essential custom instructions for GitHub Copilot · Burke Holland