I think it's safe to say that the absolute worst thing you can do is to try to be somebody else.

Firstly, attempting to be someone else has the prerequisite that your own self is not good enough, and this is extremely bad thinking. This whole process of self-improvement and self-development is not just learning that, but also understanding why, you are the most awesome person in the world. That whatever you do, whatever your values, whatever your personality, is absolutely fine. From this stems self-esteem and a shedding of the ego, which is pretty much the holy grail of PUA.

Rather than making apologies for being who you are and thus trying to be someone else who you have been told is cooler, accept who you are and be proud of it. You can take the (apparently) least cool characteristics you may have and, by being unashamed that that is your personality, make them cool. For instance, I am a huge car geek. I love every single thing about them, but more than that, I know all the really anoraky stuff as well. 0-60 time for an Enzo? Top speed of a Murcielago? Price of an M3? I'm your man.

Now, I could (and probably should!) be ashamed of this apparent geekiness, but because I'm open and honest and accept that it's part of what makes me me, not only can I accept it, but it induces others to think that I'm cool because of it. It's not just the good stuff that makes you cool (like playing the guitar or being an amazing cook), it's the geeky stuff too. Without it, you wouldn't be the overall awesome package that you are.

It's an oft-used and, if interpreted in the wrong way, disastrous, piece of advice, but be yourself. Don't apologise for who you are.