I love painting portraits more than anything else, mainly because of their ability to tell you more about a person. One of the things I like to include is photo-references, and I have a tendency to use these a lot. Popular opinion — or the loudest one anyway — holds that using photographs in a painting is cheating. Moreover, copying is another things that this community frowns upon, but you actually learn a great deal from copying. To tell you the truth, it may well be the fastest way to improve as an artist. My recommendation is to study old master paintings. You will need to be very observant in order to learn how they did it, but you can apply everything you learn here in the future. On a side note, the 10,000 hour rule is not going to apply if you are practicing wrong.