Let's be clear: proposals aren't written to be confusing on purpose, but nobody really benefits from making them clear either. I've been doing this for ten years, so let me write about the habits of my own industry.
1. The phrase "turnkey" means absolutely nothing. What is turnkey are the items listed in the proposal. Anything not listed is extra work. If the proposal doesn't itemize exactly what will be done, then the price isn't real either.
2. Be careful if the timeline is given as a single number. You should see "design 2 weeks, development 4 weeks, testing and fixes 2 weeks," not just "8 weeks." A single number is just a polite way of saying the work hasn't been planned.
3. Revision rights must be in writing. How many rounds, at which stage, and within what timeframe. If it's not written, don't expect unlimited revisions; quite the opposite: you'll get hit with extra fees at the first objection.
4. Who owns the code and content? This single sentence determines all future bargaining power in the project. Our standard is that ownership transfers to the client upon delivery; that is not the industry standard.
5. Maintenance is a separate line item and should be written as such. The system continues to live after delivery: updates, server, bug fixes. If maintenance isn't in the proposal, it doesn't mean it won't be done; it means the bill will come later.
6. The payment schedule should be tied to project milestones, not calendar dates. It should say "upon design approval," not "on the 1st of the month." Otherwise, payments proceed even if the work is delayed.
Anyone with questions, feel free to write. I'm open to criticism of our own proposals too.