Stating the Obvious...
(you could say silly, but I bet you've done some of these!)
Always remember to switch on transmitter AND receiver before launching model.
Always check that left aileron on the transmitter does actually equal left aileron on the model.
Remember to fit enough elastic bands to hold the wing down. Lapses in memory may result in fuz going straight on if you attempt a fast loop.
Make sure that the model about to be launched corresponds with the model held in your computer transmitters memory.
Always remember to put the transmitter in the car before setting out on a days flying.
Don't stand on your wing when discussing your last flight in the pits.
Don't admit to your wife/partner the real cost of that nice new model you just bought.
All of the above may result in considerable embarrassment to yourself and your bank balance!