Good question, and one that would probably generate a lot more discussion of asked in August or September.
"Equipment Rules" is a broad subject, and I can't give a blanket answer to whether or not I enforce them. If they're safety related, I try to enforce them. By that I mean that I won't let a kid play without a butt pad, or with a mouthpiece that barely covers his front teeth. I also get rid of bicep and calf bands, and won't let kids play with play cards on their belts.
There are other Equipment Rules that I'm less likely to enforce. If A breaks the huddle and I notice that the snapper has a white towel on his waist and a wideout has a blue one, I let that go. Same with untucked jerseys, although i will remind them during time outs to tuck them in.
There are two Equipment issues that are particularly challenging in our area. The first is pants that don't cover the knee. You tell the kid to pull his pants down, and when he does, and while he's standing still, the pads cover the knee. As soon as he gets in a stance or takes off running, the pants rise up above the knee. Similar situation with back pads. In between plays, the back pad is covered, but as soon as the kid runs, blocks, or does anything similar, the back pad is flapping in the wind.