Establishing my suitability to give you relationship advice: I am married with one three year old and a second child on the way. I played the field when I was younger too.
Start: How old are you both?
If this is a teenage romance, you're both experimenting with your feelings. Enjoy yourself but don't expect this to be a lifelong romance like the Hollywood movies will tell you. The most important thing you'll get out of this before it ends in a few months to years is a better understanding of yourself. DO NOT get her pregnant, you'll fuck up your life.
If this is an early twenties romance, you'll both be old enough to have had a few previous relationships under your belt. If you have but she hasn't, take it slowly and gently. If neither of you have, treat it as per a teen romance. If she has but you haven't, prepare for heartache but enjoy the ride. A woman with experience is a wonderful thing. DON'T fool around with more than one girl at a time unless they're into it too, this will always end badly, trust me on this. Enjoy the sex while you're young enough to have the stamina for it during that crazy first period of the relationship, the memories will serve you well if it ends up permanent, and if it doesn't you'll still remember those days with a small private smile.
If you're in your late twenties or early thirties, look for a stable relationship before you're past your prime. Otherwise you're going to end up as a creepy old man who spends too much time on computers. Or married to a mail-order bride that's twenty years your junior that is more of a nurse for your chronic medical conditions than a loving wife. Find a good one and play for keeps.
On picking a good girlfriend: it's the one you share the most in common with.
If you're young and new to dating, you don't have enough development to know who you're going to be as an adult. Don't expect to find someone you can spend a good sixty to eighty years with based on music taste or favorite movie. If you're in your early twenties you've probably started down the road to personal discovery and pretty much know where you'll end up landing, so date someone that is better looking and smarter than you. If you're nearing the late twenties you're past the point of no return, the doors in your life are all mostly closed and you're gonna probably stay where you are now for the rest of your life. Find someone else that understands this too and start having babies before you're old enough to be their grandparents.
Final thoughts:
Your mother-in-law is what your wife will look like in twenty to thirty years. Choose appropriately.
Bars are terrible places to meet good people, and wonderful places to meet bad people. Pick what you feel like at the time.
Make lots of friends. Their sisters, cousins, friends, sister's friends, etc. are all dating material. You might not like them but they could have a great hottie they can introduce you to.
Relax and have fun but enjoy yourself safely. Sexual diseases aren't Pokemon. Don't catch 'em all.
DON'T GET HER PREGNANT. YOU WILL FUCK UP YOUR LIFE.