There are literally thousands of books about branding (about 298,000 according to a Google Books search). You could devote a career to studying the topic, and many people have.
But some of the best, most relevant lessons are very close at hand. You need to look no farther than others in your field.
I’ve heard a number of entrepreneurs say, “we have no competitors.” Almost always, that's dangerous ego-speak. Unless your prospects have no alternative at all but to use your product or service, you have competition. (And if you’re among the innovators who truly do not, savour the moment. It won’t last.)