I know this is cliché, but first and foremost be yourself. If you put on a mask and try to present yourself as someone you're not it will only make the relationship built on a false premise. If you're funny, try to make her laugh, if you're clever, try to make her think, if you have a hobby that you devote a lot of your time to, talk about it. Be confident about the things you are knowledgeable about and humble about the things you aren't.

Don't make it all about yourself of course, ask her questions about herself and her interests. Listen intently to her answers so you can bring up her interests in later conversations. Don't be playing around on your phone or anything while talking, make it that she knows she has your attention. Make eye contact.

There's nothing creepy about talking to a woman, though they can certainly make us feel that way if they're not interested in us. If you do get rejected just hold your head high and move on. You were brave enough to take the first step knowing that rejection was a possibility. It takes a lot of guts for many men to initiate conversation with a woman they're interested in, some men find it easy but most are like you and intimidated by it.

You're asking two different questions really though. Most of the time when a man and woman become friends it doesn't progress further than that, we all know the infamous friend zone. I think you should make your intentions clear from the start, that's what has worked for me at least. If you're interested in a woman you can start with the small talk but try to be a bit flirty as well, nothing overt just something like "that shirt looks nice on you" or another small compliment, usually based on her reaction to that you can tell if she's interested. If you come on too strong many women will turn away from that and if you come off meek and unsure of yourself it will have the same effect, there's a middle ground that you'll just have to find for yourself.

In the end women are all individuals so some may prefer an athletic musclehead while others will fall in love with a sensitive poet. Play to your strengths and don't pretend to be something you're not. Sooner or later you'll find a girl who appreciates you for who you are. There will be awkward moments and rejection along the way but don't let it kill your spirit, it happens to all of us.