I shall be playing Devil's Advocate here and I will say to you... On the topic of physical image, i.e clothing, hairstyles etc, disregard what has been said.
I do, however, feel that in Grannysnatcher's post some very important things have been touched on.
Give the "Vs" to the whole makeover thing and image consultant/stylist (unless you have a serious issue, the only one that springs to mind is if you are blind), change is supposed to be gradual and most of all comfortable to you. Buy clothes that you feel comfortable in as that will make you feel better and help you in projecting a positive and confident image. There really is no need to go and break the bank by buying stupidly priced designer label clothes, although there is no harm in doing this unless they have stupidly large brand names printed across them.
I cannot stress enough the importance of wearing stuff that is comfortable to you personally and makes you feel confident. I recently got myself a new coat that I LOVE, it's not tatty or "cool", it's smart. I was on the train feeling like THE man and noticed an attractive girl (probably a 7 or 8 if you REALLY need the details) literally undressing me with her eyes. I say undressing, it was more like undressing and having the wildest sex with me

and when I left the train it looked like the poor girl was going to cry as I hadn't said anything to her (I was feeling tired and wanted to get a move on back to my flat after a long weekend)
Above all else on this subject is hygiene, keep your hair and everything else TIDY. Experiment with different hairstyles and facial hairstyles. Again, something that YOU are confident with.
Just remember, cleanliness is next to Godliness.