Ask for the money. A lot of writers starve needlessly because they are too shy or lacking in self-confidence to demand what they deserve to be paid. This is our standard contract. Learn to think like an editor. Know what editors are looking for in terms of the kinds of books they can sell.
Competition is fierce.
If you want to sell your book, you've got to think commercially. Sell now, write later. Typically, when I sell a book based on a proposal, I get half my money on signing the contract, half on delivery of a completed manuscript. I never write on spec. Always keep several projects in the pipeline.