This is an edited post I originally put on /r/pua- a guy needed some flirting tips and no-one seemed willing to help him, so I wanted to sort the brother out. Rather than leave it there to rot I thought I'd put it here where it might be of some use to someone.

I'm gona take a stab at some general guidelines here dude, but you pretty much hit the nail on the head yourself- you think too much. Gruder got it right, it's not hard, but it just takes experience to know what to look for. You said you don't know how forward you should be- this is a completely subjective problem. Every girl you talk to will have a different definition of flirting, and the only way you're going to find out what that is, is by trying your luck. As you get more experienced, your calibration and adaptability will improve which will enable you to spot patterns and think on your feet. For now, all you need to do is stop thinking and just get out there and do it. Here's a few tips, but remember they'll work better if you keep your frame fun and lightly sexual (which is pretty much the definition of flirting anyway!)

  • Initiate contact whenever possible. When you make a girl laugh, reinforce it with a gentle touch on the arm, shoulder or back. This works on a lot of levels, the most basic being that she will associate your touch with fun / laughter / feeling good. If you aren't close enough for the touch, make sure you are next time. Also, get them to touch you. I have a shaved head, and asking girls to rub it for whatever ridiculous reason (good luck, to see into the future... The more ridiculous the better) is a great way to get a laugh and initiate some contact. Find something that works for you and run with it.

  • Get her thinking sexy. Flirting becomes a lot easier when the girl is on a similar wavelength as you- ie a sexual one. A great way to instigate this is Neil Strauss' Fantasy Elicitation routine from Rules Of The Game. The (very!) basics-- you swing the conversation something like- "Don't believe everything you read- did you know there was a professor in the sixties who wrote a book about how women were incapable of sexual fantasies?! I know right?! Then this woman called Nancy Friday wrote a response called My Secret Garden- she interviewed hundreds of women about their fantasies and put them all in a book! A girl I dated read it, she told me her fantasy was...... and no, we never did end up doing that!" With any luck the girl should then start describing some fantasy of hers, after which you can talk about something completely different and let her marinade in her own sexy thoughts.

  • Pet names. Can also be combined with contact for added flirtatiousness. I use it liberally when asking for things, but always keeping it jokey and fun- put your arm around their shoulders or waist while saying something like "Darling, sugar-pie, honeybun... Fancy buying my another drink? / passing me my coat? / taking me home?" If you've kept an appropriate frame, you'll find that they'll usually reciprocate the name calling and the contact.

EDIT! If you feel this is too creepy / sleazy / not going to work (or even if you don't!) try calling her something based on where she's from / what her job is / what her hobbies are. Credit to Beemeroo82- "Something more teasy and less grimy- For instance, I met a girl in Manhattan who said she wasn't from around here and we joked about it. I called her "upstate" and she loved it." And Toby16custom- "I called this gal I was flirting with once Little Hollywood since she was going to school for acting and she ate it up." Sparklyteenvampire added, "If she reciprocates by making a nickname for you, you're golden--so make sure she has something to work with. If you call her "City", make sure she knows you're from the country. My favorite was a girl from the south I called "Sunshine"; she knew I'm from the north, so I became "Snowflake"."

  • Favours. Not strictly flirting, but psychological studies show that people will find you more attractive / like you more if they can convince themselves to do things for you. Fact. Use the Yes Ladder to help you out (look it up if you aren't familiar with it.)

EDIT 3- TIL this is called the Ben Franklin Effect - http://www.forbes.com/sites/sap/2011/11/16/do-me-a-favor-so-youll-like-me-the-reverse-psychology-of-likeability/

  • Agree and amplify. A great technique which can be used all day every day, especially when a girl is joking / flirting back / shit testing you. A good example I once heard was at a house party, the host jokingly told his target, "now if you'll excuse me, I do have other guests to be attending to..." to which she replied "ugh! You're such a terrible host!" He came back with "You have no idea! I threw a pool party last week... There were drowned naked people everywhere..." Again, the more ridiculous / lightly sexual the better, as long as you stay confident and keep smiling.

Give those a try dude, they're pretty basic but it's a good start. Keep in mind that any kind of flirting, no matter how good it is, isn't going to work on a girl who has already decided to friend-zone you. It's always going to work better on a girl you've just met- initiate your frame early! Good luck, and let us know how you get on.

Edited due to cultural differences / general female consensus.

EDIT 2- Found this great follow-up on teasing- http://www.reddit.com/r/seduction/comments/sv7tk/a_not_so_quick_guide_to_teasing_pt_1/