I like to do a prebreeding check up with the male and female. Everyone should look healthy and free from disease. Check their vents, they should be clean, the female's will be a dark pink, red or purple indicating she's ready.
A lot of people take the doe to the buck's cage and this works just fine. I prefer taking them both to a neutral pen for two reasons, some of my bucks are territorial spazes and secondly the pen allows for more room to run around--less stressful I think.
Let them go at it. You'll know when a breeding has taken place because the male will grunt and fall off (its very stupid looking). I normally let them have fun for as long as the doe is willing, then I step in. I hold the doe for a few minutes so she doesn't pee and flush anything out, then return her to her cage. I put them together again another 8 hours later to increase the odds of everything taking.
Good luck!