Is there a correct/right way to approach women?

Ok well I just started college not too long ago and im excited but also excited to meet girls. Today when I was catching the bus a girl got off when I was getting on and when we crossed paths I said "heeeey" as in just "hey" but said it in a long way lol and she completely ignored me. Was that considered disrespectful? I wasn't trying to be if I was. I'm a nice person and I have excellent manners especially towards females. So I apoligize in advance to any women who answer my question :) but anyway how should I approach a girl I like. I got over my shyness after high school :D