Do nice guys/girl finish last ?

It depends on your goals. Jerks are usually more successful financially or in politics. However, nice people are liked by more people. Though, being too nice is bad too as people would start exploiting your kindness. As it was said, combination of both will most likely serve you best. Be nice to other people so that they will like you, but also be a jerk when someone stands in your way (or tries to exploit your kindness) and there is no other way of getting rid of him/her. That way, you have better chances to be both well-liked and succesfull financially (or in politics or any other field).

Well, it would be better if you do both be a jerk or be nice sometime but not too much because too is not good. Keep the balance and people will like you.

It may also depend on your age. When I was a teenager girls liked my "take no prisoner" attitude, but as I've gotten older the girls have too. Women usually notice kind gestures and compliments, and tend to stay away from jerks. There will always be exceptions, just believe that whatever age all women love being complimented. Gifts don't hurt either.