Most Helpful Guy
Depends on how strong you come on to them. Just compliment them as they're walking, but not based on their body parts. Smile and avoid glancing downwards.
It takes courage to walk up to a girl and while some will dismiss you immediately, choose your compliments carefully.
It also depends on what area you're in. If it's a bar, walk up to her and ask if she wants a drink. Just make your intent clear. Just be confident, and accept rejection as soon as it comes.
Most Helpful Girl
I really don't understand why it's so hard.
Just don't come on too strong and learn to read her body language.