When recording and mixing, mentally divide each sound into 4 EQ sections:
• Bass (60hz-150hz)
• Low Mid (150hz-400hz)
• Hi Mid (400hz-5khz)
• Treble (5khz-16khz)
Decide which tracks or instruments don't need much representation in certain EQ sections and reduce some of that frequency. eg: Cut most of the bass and some low mid from the Hi-Hats and cymbals from an organic drum kit. This will reduce the bleed from the kick drum and leave more room for the direct kick drum mic. Electronic drums and samples usually don't need as much reduction because they are isolated from the other drums.
Your mixes will gain a lot of clarity with a few db of low mid reduction on muddy or muffled sounding instruments or vocals.
Lightly boost EQ sections that can enhance certain tracks. eg: Boost a little treble on vocals recorded with a dynamic mic or boost some low mid on a snare. Try to use a shelving EQ or a wider bandwidth for boosting that affects a lot of the frequencies around the chosen frequency so it feels more like a general treble or bass boost and don't boost too much.
~ The Good, The Bad and the Ugly ~
Bass: Good sounds Warm, Bad sounds Boomy
Low Mid: Good sounds Powerful, Bad sounds Muffled
Hi Mid: Good sounds Clear, Bad sounds Harsh
Treble: Good sounds Bright, Bad sounds Brittle
and I should know... cause Treble is my middle name.