The skewer goes through the hub, and then binds to the dropouts when the QR mechanism is engaged. How I do it is spin the nut side until its loosely finger tight, then start pressing in the lever to see how much binding pressure its applying. I like to keep the lever at a certain spot cause that spot is what the local LBS said is the deepest the lever can go, and thus is most effective. If its pressing in too easily, I start tightening the nut side, and then keep spinning and depressing, spinning and depressing, until I am satisfied that the compression of the QR mech is sufficient. Now my LBS likes to be thorough, so they installed it double ass tight (must have used a wrench to tighten the nut), but I find that to be a bit excessive. You just want to ensure that the skewer is securely binding to both dropouts.

If you flip the bike upside down and dont engage the qr at all and spin the wheel, does the wheel bind against the brakes or the fork , spin roughly, or wobble like its out of true?