When making burgers, look for a mince that has a fair percentage of fat in it. The fat melts during frying and keeps the patty moist, as well as holding the patty shape. Cuts such as chuck steak have a generous marbling of fat throughout them; ask your butcher to mince them for you.
'Best quality' lean mince has very little fat and can make your burgers too dry. If you prefer lean mince, add extras such as eggs and breadcrumbs (or rice flour for gluten-free diets) to hold the patty together, and add a little more sauce for moisture.
When you prepare the patties, handle the meat as quickly and lightly as possible, and with cool, clean hands. This will stop the meat sticking to them too much. For added taste, dust the finished patty with polenta, which will crisp up when fried, giving a subtle crunch.
Try it out with this recipe: Goat's cheese burgers with watercress salad.