Your order of what to do is out of order. Before going for cosmetics, make sure the bike fits you and rides well. If both of those requirements are met, then make it look good. You can learn a bit more about this by looking through Test Riding A Vintage Bicycle.

Don't do what I did the first time I built up an old bike. It was too big for me, had a bent frame/fork and I went to the trouble to paint the bike before I learned that it did not fit or ride worth beans.