In reply to pghmike,

The 3 blade props are for better torque. But due to the fact that they have one blade more they are "heavier" for your engine. So If for example your engine is for 60-70size works well with 12X6 two blade and you use a good performance fuel with mixture containing Nitro 15%you can use a 10X6 or 11X6 or 12X4, 3 blade. If you use cheaper fuel then try not to stress your engne too much and use 10X6.
Now as far as ballancing your prop the first thing you should do is buying a prop-ballancer!! and a lot of sandpaper! Then try to sand the inner prop surface without destroying the leading edge. After you make it "lean" with sandng with proper sandpaper (it depends what prop you are sanding in order to choose the right sandpaper - if the prop is wood or plastic)and after the prop ballances on the prop ballancer you have a "perfect static ballance".

Cheers
Johnnie