Bring in the big guns
People love to be needed, and love to be thought of as a leader in their field even more. If you could use a hand reaching a goal, ask around until you find someone in the field who seems universally respected and on the ball. Call them up and explain that you are trying to break into the field (be sure and choose someone for whom you will not represent up-and-coming competition) and that you've heard that they are the as the go-to person for the inside scoop. Ask them for what's known as an "informational interview", and offer to treat them to lunch so that you don't take up their valuable work time. Pick the nicest place within your budget, or ask where they like to eat - and don't forget your checkbook or credit card (call the restaurant first if you're unfamiliar with the place, to ensure your card or check will be accepted). Have a backup payment option on hand, just in case their credit card swiper is down that day. If your target decides to meet in their office, make sure you don't take up any more of their time than you originally asked for, unless they specifically ask you to stay on - and even then, use good judgment about overstaying your welcome.
Prepare a list of questions beforehand and make sure that you listen carefully to everything they say. Taking notes is nothing if not flattering to the speaker, so feel free to do so. If they start to wander off on a conversational tangent, a good way to bring them back on target is to say something like "Wow, someday I'd really love to hear all about (whatever they're talking about), but since I know you're very busy, I really have to ask you about (your question) before you/I have to leave."
After the interview, write a brief thank you note (on paper, not email) and get it in the mail that day or the very next morning at the latest. Then add that person to your network list!