Research on the Internet
The Internet can be your friend. Use it for what it is, a tool. Most attorneys have a place in cyberspace that they call home. This is their first chance to show you what an amazing attorney they are. You can typically find a list of accomplishments and achievements on their webpage. Look at several different attorneys' webpages and try to narrow it down to a handful that have the experience and know how that you need.
Everyone knows someone that has been through a divorce or custody battle. Ask around. Referrals are a great place to find attorneys that will work for you. You can ask about the attorneys that are on your list from above and see if your friends have any experience with them.
Don't believe everything you hear
The best attorneys will have a good reputation with some people and a bad reputation with others. It is all a matter of which side of the case they were on. I think it is important to meet potential attorneys in person. Call and schedule a consultation. See who calls you back first. See which office is professional and handles your call in an appropriate manner. A responsive call is a good sign of things to come.
Kick the tires.
Just like buying a car, you don't walk up to a car and simply say I'll buy it. I think it is important to meet at least two attorneys so that you can get a feel for what to expect. Ask questions about how they operate. See what their plan of action is and how they plan on getting you to the finish line. Use this as an opportunity to interview them and have your questions answered. This is your time to decide whether you think you can work with them. Go with your gut, it is usually right.