I'm getting there, was below 10 stone, now I'm close to 10 1/2. The physical side is easy to improve, dress nice, exercise, lift weights, eat more/less.
Other, and generally more important factors require a little more practice. Posture, body language, projecting your voice, basically inner confidence.
You could physically look awesome and attractive, but if you didn't feel that way or act it, then people wouldn't treat you as such. Of course it works on the flip reverse, if you're not the best looking person, nor the most physically fit, but feel awesome then people are more likely to respond to how you feel.
So if you want to feel better about yourself, changing your physical appearance will only go so far. You need to change how you see yourself.