Definitely try to move stuff around to help reduce the weight you have to add to balance it out. First, I try to move stuff around to balance it and keep the weight the same, then if all else fails, I try to get something useful out of any weight I have to add (larger/heavier batteries, metal gear servos, larger engine, etc.)

Here's some tricks I've used:

Tail heavy:
1) Move battery as far front as possible
2) Move engine foward on the mount
3) Move receiver/servos forward if possible
4) Install a bigger engine!

Nose heavy:
1) Move battery as far back in the tail as possible, & use larger battery if necessary
2) Install metal gear servos (heavier) if there are any mounted behind the CG
3) Move engine back on the mount (closer to the firewall)