There are different ways you can help contributing to Cutter:
Make a clear description of the bug/feature, use screenshots, send binaries, etc. This will help us improve the software for you. You can create an issue by clicking on this link.
Note that cutter is still under development and many parts of the code are to be improved. The best way is to check the opened issues here or discuss with rizinorg team. Please follow our contribution guidelines: https://cutter.re/docs/contributing.html
The documentation is something important for newcomers. As of today the documentation can be found here and it stands in the docs folder. The API Reference is automatically generated from the source code, so it is strongly advised to document your code. Check issues marked as "Documentation" on our issues list.
You can help Cutter by adding translations to the project! We use the Crowdin platform to help us share translations. Feel free to contribute and add translations to the project. If you need to add a language, ask any rizinorg developer.