here is your GENERAL advice.....
these ranges are really rough....REALLY ROUGH.
20 - 40 = danger zone for a studio with poor acoustics.....you need a god sub to justifiably work in this area.
40 - 80 = low end. if you can't hear it, or hear too much of it in your room, get some good headphones.
80 - 150 = the beginnings of mud. 100 - 150 especially can make things nasty.
150 - 300 = mud, boxie......but be careful, if you cut too much out, the mix loses power and impact.
300 - 600 = chesty, if that makes sense. keep in mind that around 500 Hz is the speaking voice of a bass guitar, but it can also be the HONK of a bass guitar.
600 - 1k = nasally. you gotta singer that's sounding nasally, cut around 800 and see if it helps....also good to watch out for in some acoustic guitars.
1k - 3.5k = definition. 3.5k is a bit high for this, but whatever. many things will enjoy a 1.5k - 2k boost for a little definition. kick drum, bass git, snare......becareful how many things you try to jam in this region.
3.5k - 5k = the beginning of presence. 5k can add the appearance of loudness to the mix, but is also very fatiguing to listen to.
5k - 8k = presence.
8k - 15k = sizzle
15k - 20k = air
key thing here is that these ranges are very ROUGH, people will chop up my list and redefine it all day.
you need to dive in and start hearing this stuff for yourself. start figuring out what you like and don't like.