Don't: Add cold meat to a hot pan. Adding cold meat to your pan just cools your pan and may cause your meat to release those juices. Let your meat come to room temperature before cooking for best results.
Don't: Add meat to a cold pan. Heat your pan until it is HOT before adding your meat.
Don't: Overcrowd your pan (see photo). If you are cooking more than 1 pound of meat, break it into batches. Make sure you allow the pan to reheat between batches.
Don't: Walk away! If you have followed the first 4 steps, browning your meat will not take very long. Your goal is to sear the surface of the meat to lock in those juices. Unless the recipe calls for the meat to be cooked through, there is no need to move it around that pan for 10 minutes until you are sure it is well-done. Chances are, your ground meat has another round of cooking in some liquid (like chili) or a casserole dish, which will ensure it gets fully cooked before serving.
Do: Use cast iron cookware. It gets very hot, cooks fairly evenly, and boasts great nonstick properties if you have seasoned your pan properly.
Photo: An overcrowded pan, courtesy crschmidt on Flickr.