As an author, I've been asked "How did you get published?" a lot. I have a couple of pat answers for people who don't really know me, and they're perfectly good answers. Just not complete answers. 1) The long answer. I say, "Write a book. Submit your queries and while you're waiting to hear from all the agents and editors that you (of course) researched to be sure you've targeted the right people, write another book. Rinse and repeat until someone asks to see more. Send the best proposal or full manuscript you're capable of crafting at that time. (Be sure it's whatever they ask for, exactly as they ask for it, and no more or less than what they ask for.) Write another book. Rinse and repeat until you get an offer. I don't go beyond that point, because people don't really want to know about contracts, etc. They just want to know how to get 'the call'. 2) My other answer is, "Work your tail off, and Don't. Give. Up....
READ. REVIEW. REPEAT.