I always train abs before I start working out. I use it as part of my warm up. I do some regular crunches, then I do some like V-ups with a weight in my hand. Then I do some leg raises, and finish with leg lifts on an incline board, oh and if I have time some side bends with a weight. Like others have pointed out, I always have had abs, but they are more pronounced since I started working them a bit. It is also related to genetics, as I am not very good at with staying away from junk food, but still have abs.