Do you have a nearby store which has a meat market, not just packaged meat in a particular aisle?
If so, you may want to start there. Most meat markets will be glad to help you pick out a good cut of meat, especially if you let them know you are new to the process and want advice as to what cut is best for the recipe you plan to prepare.
If not, I generally look for meat which has good color and little fat; I tend to avoid packages which have a lot of blood leakage but that's just a personal preference. Your best bet (if you don't get assistance from the butcher) is really going to be trial and error so you can learn what you like - everybody's preference is different.