Your salary should be basic, covering your costs and giving you a bit of spending money. This assumes you're working full time for the startup. Remember that the bigger picture is equity.
Some good tips here: http://blog.guykawasaki.com/2007/07/how-to-write-a-.html
Whatever you do don't spend a month writing a 60 page document. Keep it short and sweet. Use lots of bullet points / bold highlighting to ease readability. No complex multi-idea paragraphs. And most of all, just answer the key questions.
Good luck.