I know this is a generalization, but I have found that those that compete regularly, are a good source for answers to problems. To be competitive, you just cannot have problems. You have to have everything boil down to your flying. Any mechanical issues will kill you in competition.
When I flew CL combat, we would spend more time practicing our engine starts/pit procedures than actually flying. As pitting is a huge part of the event. Needless to say, this gets you good at tuning engines.