Spectrum is currently under heavy development. This means there are a lot of opportunities for contribution, but it can be difficult to figure out where to start, especially since there's not a complete system available to experiment with yet.
Here are some ideas for contributions, roughly ordered by priority. If working on any of these appeals to you, even if you don't understand all the parts involved, we'd be happy to provide mentorship and support. Just reach out on IRC or email firstname.lastname@example.org.
This list is nowhere near exhaustive. If there's anything else you're interested in working on, or just nothing on this list appeals to you or fits your skillset, get in touch, and we can advise you on how you might be able to help out.
Permission is granted to copy, distribute and/or modify this document under either the terms of the Creative Commons Attribution-ShareAlike 4.0 International License, or the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.