One of the biggest misshaps I see as a trend is lack of willingness to inspect your gear and double check your actions before takeoff.
We had 2 90 size helis bite it over new FoolishTaba servo horns falling off and myself? This weekend I caught myself ready to lift off with the GlowPlug STILL in the connector

, the combination of heat from the running motor AND the Current applied to the plug it would have overheated in two minutes causing a NON volitional Auto rotation landing.
Being a begginer with Auto Rotate it would have been a wreck.
My Raptor Titan 50 almost became a Craptor!!
Starting up a IC engine next to your vehicle is another disaster waiting for a happening, One weekend a Reciever battery wire connection decided to "Go-South" 'during' takeoff and almost took out the windshield

.
No, it wasn't me but that doesn't matter I "HAVE" done this before and since then I run a cable from my car battery out to the flight line and forgo the lazy-ness , call it learn from others mistakes, it's cheaper that way.
Flying too close? So far so good, I have not the nerve to fly shorter then 50 feet accept on a landing sometimes it's closer [presbiopia $^cks].
My flying has a long way to go, and at that, does a "Skilled" pilot mean it's OK to take chances? I think not, but being human we all get foolish in a week moment, witch is why I like small groups 3 people or less.
NO KIDS!! or pets would be ideal. And OH YA, AMA insurance doesn't hurt either. #867896
Scott