Sure, the best rule is to concentrate on what you enjoy/excel at, and pay someone to do the rest.
Me? I'm an inveterate dabbler and can't keep my hands off the knobs.
And yes, when using a reference track it's important to be honest and realistic about the sound you expect to achieve. Cheap/free mastering plugins won't get you the glossy result that the big boys can achieve, with all their gear and experience. But picking the reference tracks wisely can still get you a good aiming point, and help calibrate your ears. Personally I prefer the more informal sound that a less-than-perfect room and a sparse mix brings to the kind of music I make, rather than trying to achieve the surgically-clean, diamond-polished, loudness-maximized result that we hear on store-boughten CDs.
It's all about serving the music (and having fun).
Cheers
-Glenn