Best way to fix grip size

[montrealtennis]

What is the best way to increase grip size form 3/8 to 1/2?

Is the heat shrink sleeve the best way to go to increase the size? Can it be done by yourself and still get good results. Since I'll have to re grip? Will will balance be effected in enough to feel it?
I cant do 2 layers of over grip since I'm gonna put a layer of over grip on the 1/2 for the right feel.

 

[Klatu Verata Necktie]

You could apply a heat shrink yourself, but any good pro shop should be able to do it for you for a very modest fee.

It will add a bit of weight to your stick. How much that weight affects your feel depends on how sensitive you are. Since the added weight is in the handle and not the head, it usually isn't that significant.

Two overgrips will increase the size considerably, but you will lose much of the bevel feel.