I agree with Xero. That's the main downfall with all the pick-up-women tricks. They have you acting like you're someone you're not. Therefore, you attract women who are totally wrong for who you actually are.
Nice guys fall into distinct categories. One is the guy who has manners and a conscience and he chooses his behavior based on what he thinks is right. The second type is soft because he is afraid to offend anyone. If you're the latter, then I suggest you check out a great book, "Wild at Heart" by John Eldredge. It can give you a whole new perspective on masculine identity.
If you're mainly insecure around women, then I would recommend you check out "Intimate Connections" by David Burns. If you are confident but just have difficulty presenting yourself as boyfriend material, you might want to check out "Love Tactics" by Thomas McKnight. Chances are you probably just need some tweaking on your skills and you're obviously bright enough to do this on your own. Interacting with women is ultimately a learned skill, and there's no reason you can't be self-taught. Basically you use the materials to get ideas and then you have to go out and practice them.
One way to prevent dating relationships from entering the friend zone is to get physical quickly. And I don't mean sexual. Make sure to initiate a full kiss, at least by the second date. That definitely indicates you aren't interested in the friend zone. Most guys fall into that trap by trying to be too nice, which is a problem. You want to treat her with respect, but make it clear from the start that you're not going for the friend zone.
Love Tactics and Intimate Connections helped me take my social life from non-existent to very active in about six months of effort. The concepts are based on cognitive-behavioral therapy and they work if you're willing to put them into practice.
Best wishes. If you have any further questions, please hit us back. Chances are someone here knows.