Joe, as others have said, it takes lot's of practise, but you could also read some tips given here: http://www.askthecameraman.net/Practical/The_7_Steps_To_Becoming_A_Professional_Cameraman/
If you want to know about the first steps, you could try reading this link.. It's not really for a cinematographer but for an ENG cameraman, but I think the same basics apply:
http://www.askthecameraman.net/Practical/The_7_Steps_To_Becoming_A_Professional_Cameraman/