So for sound design, if you can make a list of desired sounds with a short description that would be great. Also if you have something specific that you're drawing inspiration from and have some reference material (where you liked the sounds or want it to sound "like this") send that my way. Youtube videos or the like is perfectly fine for reference material. I can do limited voice over as well, so if you're wanting some light vocals like grunts or generic celebratory sounds I can probably manage that. I'll likely synthesize most of the sounds, but any samples I use will be modified and obtained legally. Basically means you won't need licensing or the like.
Also, if you're planning on making the game free, the only thing I want is credit in-game and maybe contact info. If you're planning on selling the game I would like us to do deferred payment. Basically means if you don't make money, neither do I, but if your game takes off a sells like hot cakes, I'll get some kickback. I'll probably avoid percentage of sales since most are averse and just go with a tiered fee system.
If you prefer we could go with percentage since it's simpler to contract. Ultimately I don't expect to get paid, but doing a basic contract with something like this will protect both of us. Let me know if this sounds okay to you. If you're not feeling comfortable with anything I've suggested please let me know. Also, feel free to send that list to my personal email. If you wanted to do a google doc so that you can update it at anytime that's cool too.