A combination of things, but experience (just doing it) - is the most important. Of course, having initial, theoretical knowledge is important. Doing it is not that difficult if you simply learn to expect unexpected and double check and triple check things even if lenders do assure you that there is no problem. Also, study blogs - there is plenty of good information there. Here is a useful link: http://activerain.com/blogsview/190718/Credit-consequences-of-the And of course - have patience. Good luck.