From my experience,... the more you want for a g/f, the harder it gets. Just sit back, enjoy some casual flirting / talking,.. and WHAM! When you least expect it,... you find her.
I honestly know how you feel. Its the worst feeling in the world.
It was killed me being single.
Be confident (but no arrogant). smile lots. Let her talk and be interested, compliment everything she says, compliment everything about her, be generous (buy her dinner) and most of all,... show her respect.
This might sound really strange but when I was single, I needed a nice shirt for a date the following evening.
After finding a nice shirt I went on the date and everything went really well. Ultimately it didn't work out (due to me getting the Supra stuck in the snow and having to hitch a ride home with date,.. yep, true story) but the shirt seemed to give me confidence,... and so every date I had from that point on, I made and effort to buy a shirt, trousers, jacket or whatever from the same shop. Maybe I thought it was 'lucky',.... but it did give me confidence which helps.
So find something or technique that helps you and gives you confidence to be that little bit better on the date.
Good luck you handsome man!