A good idea on balancing tires is, instead of using balancing tape that works ok, but can come off, try using hot glue instead. When after applying you use to much, it will still be warm enough to take a little off. It can also be applied in spots where tape cannot be.
The best thing for reinforcing bodies and wings is to use Sportsman's Goop (adhesive & sealant found at K mart's for about $3.00). I have found that the Sportsman's Goop is tougher than regular Shoe Goop.
Instead of using a antenna cap which can come off, slide a piece of fuel tubing over the antenna and wire and it will stay put.
The best way I have found to hold your battery in place is to use two 1 1/4 rubber o rings found at most stores like Home Depot or Lowes Hardware. It let's you change batteries in a snap and they last almost forever.
If you're dogbones are loose and tend to fall out plae a little piece of plastic from a wire bolt in-between where the dogbone meets the transmission will tighten it up until you have a chance to go out and buy one.
Drill a very small hole near the body clips. Tie a piece of string on to the body clips then slide the string through the small hole you drilled tie it off. You will never loose those clips again.
Try using safety pins instead of body clips. They don't come off like the clips can in a crash. And you can buy them in mass quantities.
Use a medium paper clip instead of a body clip, they stay on even through a heavy crash.