First, you put it on the plane.

Then you nose-over on take-off, break the prop.

Buy a new one.

Repeat until you happen to buy a prop that is balanced ....

Joking. Have a look at:

http://www.bollyprops.com/propbal.html

Also there are some informative threads on the Questions and answers....

do a search for [link=http://www.rcuniverse.com/forum/searchpro.asp?phrase=prop+balancing&forumid=ALL&pr oduct=&topicreply=both&message=both&author=&timefr ame=%3E&timefilter=0&language=single&top=300&crite ria=AND&minRank=10&submitbutton=+OK+]Prop Balancing[/link]

gus

P.S. Everything I have read indicates that you should NEVER alter the width or length of a prop. Also, you should never add or remove weight from the "flat" side of the propellor (the side closest to the engine). To change the balance, either sand the airfoil side, or add weight (using CA, epoxy, paint, dope, nail-polish, etc) to the airfoil side.

Apparently, changing the pitch, chord, and length of the prop all have a more significant effect on the "dynamic balance" of the prop than changing the airfoil.