Starter Kit : Motor & Model Care.
Most racing tips are elementary but how often do we forget.
Before each race meeting, check the condition of your radio batteries. During the Winter lay-up, charge them occasionally.
Check the control surfaces for any slop. That last cartwheel landing you had at the last race meeting could have dislodged something.
Always use a filter in the fuel line. Take the tubing off the model side of the filter to fill the tank. Check the tubes for leaks. Always surround the tank in foam or sponge. Vibration causes foaming and inconsistent motor runs.
Never store your model nose down. The residue from the silencer will run back into the motor (very corrosive).
Set the model up to fly with the least possible control movements. Use differential if your transmitter has it. Every control input causes drag and slows the model.
Check the model after every landing for damage. Including the prop. Balance the propeller, Any excessive vibration will slow the motor. It does not do your radio much good either.
Make sure you have a spare plug and spanner in your model box. Check the plug before you go to the start line.
After a race meeting, check the model, take out the glow plug and squirt some after run oil into the head and carb. Leave the plug loose to remind you it has been done.
If you do all of the above you should go a long way towards having trouble free racing.