Yes.
I used to do it quite regularly in my youth.
Although to be fair anything I changed to was a variation of my own personality and I just experimented with letting different sides out.
It's the same prinicpal as if you're depressed you paste a smile on your face. Or if you lack confidence you walk down the street like not only do you own it but people should also be asking your permission to use it... Eventually it becomes second nature and you actually end up feeling like that.
But it can back fire on you. Do you actually want to be that image in your head? Is that image in your head likeable? And is that image actually a part of your personality on the inside or is it completely made up? If it is completely made up then people will see through you in a nano second.
Concentrate on the things you like about yourself, perhaps you have a cheeky sense of humour but you're scared to show it or something and try and bring that side of you out.
But never try to be something you're not, you will come across as fake.
If it's a confidence thing then there's loads of self help books out there, I don't rate them but I have a friend who swears by then... mind you, she also goes for regular colonics....
Anyway, good luck to you either way tiddler.