If you run into unexpected behavior or run into a bug please report it. All bugs are kept track of on our issue tracker. You can add a bug report there or if you are not sure it's a bug send an email to the developer mailing list.
If you are interested in contributing fixes, code or documentation to SunPy please checkout our developer guide. SunPy uses a distributed version control system called Git and the code is hosted on GitHub. To get started create an account on github and fork SunPy then submit your changes via a pull request. If you are unfamiliar with Git and GitHub our developer documentation provides a sample workflow but you can also find lots of tutorials online. Please read up on our Coding Standards before getting started. You can browse our issue list or our wishlist to find something that you can tackle. Please send a quick email to the dev list or stop by the chat room to let people know what you are planning on working on (see the Help section).
If you have an idea for a major enhancement or a proposed change to SunPy please consider submitting an SEP. This process is modeled after the Python Enhancement Proposals (PEPs) and provides a structured proposal for the SunPy community to evaluate your idea. You can find the template and more information about SEPs in the appropriate SunPy repository. SEPs are submitted as pull requests into that repository.