Most contractors will meet with you to go over the construction schedule and break down all of the costs. This is a great opportunity to save! Sometimes, contractors will assume you want things you don't, and you can often find elements of the project that you can do yourself or put off until later, when you have more money on hand.
When you go line by line through the budget, don't be shy about questioning anything that you don't understand. Your contractor may have assumed that you want crown molding in your renovated space, for example. If you don't care about crown molding, you can save hundreds of dollars just by taking it off of the quote.
This is also your opportunity to decide which parts of the project, if any, you want to take on yourself and discuss anything you want to source for yourself. Going the do-it-yourself route means extra work for you, either on site or at the home improvement store, but it's worth the extra effort if it means the difference between being able to afford your project or having to cut things out that you really wanted. When you're taking on any part of a construction project, you need to communicate frequently with your contractors and make sure that you lay out your responsibilities clearly from the start. If the project ends up delayed because you didn't know you needed that bathroom vanity on site by a certain date, it can cost you money.