Just a quick note on EQ. These are only generalisations.
It is GENERALLY better to cut than EQ, it doesn't mean you should NEVER boost. Certainly if you're looking for a natural sound and a balanced mix.
If boosting, it is better to use a wider frequency band (Q), if cutting, it is better to use a narrow band (Q). That's why the hybrid QuadEQ is set the way it is.
If you boost frequency on one instrument, it's a good idea to cut a similar frequency in another competing instrument. It's often about making space for each other.
I picked up a tip from Scott G. that I now use all the time. Set the plot resolution of the QuadEQ to 6dB. It defaults to Auto. If it's set to Auto, it is not easy to compare the different track's EQ at a glance. The graphs may look a similar shape, but one may be boosting 4dB, and another 18dB. If you set it to six dB, then yo get an idea o the relative cuts and boosts, plus it also warns you if you are making more than a 6 dB alteration. If you are, it MAY be worth looking at the source material, regardless of what others may say.
I didn't say NEVER boost, I add subtle boosts all the time, just be aware, as tkx5050 pointed out, that louder can be perceived as better.
Also beware of the solo button. It's best to listen in context of the mix.
There are lots of other pointers that I found helped with EQ, but these are just the ones relating to cutting and boosting.