A lot of good advice from these guys so definitely read them all thoroughly.
I'm not the best at mixing but I seem to get it done and often get complimented on it, so I'll give some simple advice as a 4 year novice.
I personally focus on what exaclty you're trying to accomplish, what sound you want, etc. If you're going for a house beat, investigate house beats, think about what processing and balance they use to acheive their sounds.
But don't get overly techical, because its ALL about HOW IT SOUNDS. If it sounds bad it doesn't matter what technique you're using, its just bad. So try and do what you think sounds good, and what you want, cause it is both a technical and artistic skill.
So try and become familiar with the plethora of techniques people use, maybe by challenging yourself by doing multiple genres like orchestral or different electronic, and use them appropriately for what you want.
For example, when I do hip hop, I often use compressed breakbeats that are choppy or old sounding. But when I'm doing a breakbeat in a house song I usually keep it tight, and less compressed to give it more of an energetic sound.
I hope some of this helps!