First and foremost, trust your ears. There is no right or wrong. Second is realising that 99% of your crowd won’t notice either way. What they notice is when you make mistakes and even then they’ll move on and forget it real quick. I have never heard anybody ever leave a party saying “wow, that DJ was really bad (or really awesome) with his/her EQ use!).
There is a generation and genre of DJs who use every button on mixer/controller and do so all of the time. Imho most of what they are doing is not contributing to the quality of their set, especially in light of the fact that 99% of the audience doesn’t notice/care about that.
The 1% that does notice/care are other DJs, who’ll find something to gripe anyway. Don’t have to worry about other DJs that aren’t on the decks.
I keep my EQ use to a minimum. Little low EQ, the occasional snippet of high.
I also have a live sound and studio engineering background. Here you are taught that “less is more”. Boosting EQ is something hardly ever done. Reason for this is that the human ear is much more sensitive to boost than cut. So emphasising the mids is better done by leaving the mids where they are and taking out some fo the surrounding frequencies (low and high in this case). Boosting is very tricky in that it is so easy to totally throw the balance of your sound off and audibly so. At that point people will not notice consciously, but they will “sense” something isn’t quite right.
With most of the energy of any music being in the low bits, it pays to move some low end out of the way on the incoming track so you don’t raise the overal value too much. Then slowly transition to the low end on the incoming track keeping the overall low end level about the same. It’s good and time-honored practice. It also prevents the “dip” you can experience at the end of a transition. You can play with CUTTING EQ on the outgoing track a bit more to make it even smoother. But that all depends on whether you want to be busy turning knobs or with looking at the crowd, interacting with them and contemplating the direction to take your set.
Hope that helps some.
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