The main problem I hear with people and their home-made shit is problem with vocals. Either they sound like shit or not mixed right. Also the volume leveling of individual instruments. I hear some shit and I hear superloud hi-hats, washed out snare with no energy, bassline drowning out the whole beat,etc... Just over or under exaggerations on certain volumes.
I think everything else can be done decently on your own at track level, if you have any common sense knowledge. The panning of instruments, levels, EQ, Compression, etc... You SHOULD know if your shit is clipping. Main thing though, try to get your shit sounding as best as possible without resorting to too much FX like compression/EQ. Record it right in the first place or use the best possible sounds from the get go. If your drum sounds sound wack, ditch em. There's also nothing wrong IMO with using compression at the track level, especially if your trying to go after some sort of effect or add more emphasis. I usually always use it to glue my drums together especially or add some pop to a snare/clap.