I EQ monitors a bit different with suprising results.
I find a .pdf sheet or other documentation for the model monitor I'm using. Using a 31 band, sometimes also a parametric, I'll invert the response curve of the monitors to attempt to get them flat. I then place a notch at either around 4k or 8k depending on the mic I'm using, and also roll off between 3 and 6dB at 250Hz 1/2 to 1/3 octave wide. I also place a low cut filter at 150 to keep the monitor wash from muddying up the house.
Now that you've said you've got this set up in the basement, it sheds light on your other two posts from this evening.
Small rooms have nodes that reinforce certain wavelengths (frequencies) allowing them to sound boomy. Having your mains, subs and monitors all in your basement would definately cause your feedback issues. A garage where you can open the overhead door and point your mains outside would be a better option. The ideal option would be to get into a venue really early, or pay someone to come set it up for you and give you some pointers.
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