I've been reading over some proposals for software projects recently and I'm a little concerned by what I've seen. Often I feel that proposals have been rushed and/or poorly thought out.

It's very possible that proposals don't need to look like a basket of fruit, but if your pitching for work or seeking approval for funding, there has to be some guidelines available for what constitutes a "decent" proposal.

I was wondering if anyone was aware of good guidelines for writing software proposals or could possibly point me at books/websites etc?