I'm trying to hone my EQ skills and am having a hard time.

Many guides suggest certain frequencies to EQ to acheive certain effects
(though I understand these are totally subjective they're a good starting
point for things to try).

I keep reading (on potentially unreliable websites found through google)
that it's usually best to make broadband cuts/boosts to signals except when
notching out ringing. One guide suggested making it a goal to not use a Q
greater than 1.4

Suppose I have a guitar track which has some 200 - 250Hz mud in it that I
wan't to EQ out. Suppose the guitar track is also masking my vocal so I want
to cut at say 750Hz. If I'm using Q = 1.4 like suggested then i'm basically
taking out the whole low end of the guitar... it seems more logical (and
sounds better to me) to do more narrow band (Q = 6ish) work for stuff like
this.

Any comments?

Dave