There's a lot of ways you can "be yourself" that are or can be congruent with the image of yourself. There's both an upside and a downside.
Upside:
It can mean "don't try so hard", "just have fun", "be indifferent to the outcome", "don't care"
It really all comes down to the Mindset. If you have a mindset that is congruent with your core beliefs, then pretty much half the work is done. If you are already a cool guy and want to pick up a chick that's out of your league, don't try doing stuff that isn't congruent to your core beliefs. In the end, that's very attractive.
Downside :
By being yourself it could also mean "self-loathing, self-defeatist, low confidence AFC, ". That's a BIG NO-NO !!!! And you have to do something about it.