How to know what type of jeans to buy?

Like I know there are like different styles like bootcut, low rise and stuff like that, but how do you know which looks the best on you and what is most comfortable? I am a boy, I'm 153 pounds, I'm 6'3 and I run xc, track, play basketball and tennis. I guess I have long legs and yeah I have no idea how to find jeans. Help?