how many of you write your own contracts?
My guess is that the answer of people composing for a living in the industry would be "none of us."
As jbadams points out, a proper contract, complete with proper use of legal terms is not something you want to do on your own.
Now, that said, if the question is "How many of you review, modify and sign game contracts without consulting a lawyer" the answer would then be "most of us."
In fact, that exact question came up at GameSoundCon last week. All the panelists said they reviewed their own contracts. But all also said that they were very familiar with typical game music contract issues and clauses. We have learned over the years what is typical and what is unusual and what really raises a red flag. If I don't see any of those, I typically go ahead and sign. So if you are quite familiar with what standard terms are for work for hire, music licensing and ancillary usages, then it's probably fine to review it yourself. If not, for your first one, you may want to consult with an entertainment software attorney, so they can walk you through typical agreements.
Now a slightly different matter is if you are doing a very small/indy game, sometims those are done without formal contracts (yes, a bad idea, but sometimes understandable-- It makes no sense to spend $500 on a lawyer for a game you're making $500 on). In those cases, at the very lease, you can write (as jbadams says) a plain english letter/email, bullet point format, spelling out what the agreement is. Don't try to use legalese. And also make it a newly composed email (not a "reply" as part of a long thread).
(I am also not a lawyer, and this is not legal advice)