Contributions are very welcome. It can be a good way to get involved with really cool projects further on. There are still many features that could be implemented.
Whatever you feel is wrong with the SDK, create an issue for it. If you have a proposal for a change that solves the issue, feel free to include it (See issue template).
Clone the repo and mess around with the code. When you have created something cool, please make a pull request. We'll discuss how we can integrate your changes.
Please let us know what you are working on. If you have project using godot-solana-sdk let me know by posting in discussions section. I will save all projects in the readme and will follow your progress.
There are no rules for contributing really. Use your own way to format and structure. If you follow the code of conduct, you are free. Use discussions page if you have any questions and discord for further communication. Don't hesitate!