Most products don't need a whole book:

1) Use a mature, well-designed GUI framework. Especially if you don't have a designer it's unlikely that novel interactions or an unusual visual design will be a key selling point for your product.

2) Find a half-dozen folks from your target user audience or proxies who are as similar as possible. Give them a task to do with your product/prototype while you watch. Let them talk aloud without interrupting. Do this early and often.

If you can do those two things you will be ahead of most consumer products and vastly ahead of most enterprise products.