Bicycle Mechanics - putting wheels back into dropouts.. how perfect?

hi, another newbie q:

when placing wheels back on the bike, how would a bit of crookedness affect ride, safety issues, etc?
especially noticable with rear wheel w/ derailleur tension.. i believe i have the hubs placed as far inside the dropouts as possible. but since i'm using my knees to pull the wheel in the slots while tightening, i never know if i lose the slightest mm or so... what kind of factor does a slightly crooked wheel make in the ride?

thanks.

Difference will be a slight increase in rolling friction as the tire tread has to
scrub on the pavement enough to straighten itself out. There would be an
increased rate of tread wear associated with this also. Not very feasible to
quantify as tire treads vary enormously, but one could say that such as an
ATB with large mobile chunks of tread is more affected than a slick.

Put the bike on the ground/floor, loosen the skewers and press down on the bike to seat the hubs properly in the dropouts, then tighten.

Yeah, crooked can mess with shifting too. Don't let your bike sit only partially in the dropouts.

Let gravity help you line things up. Shift to your smallest cog before you remove the rear wheel, giving you less distance to move the cassetted out of the way. When reinstallijng, hold the bike with one hand by the seat tube or seat post, and let it hang. Roll your wheel in with the other hand, swing the bike slightly to get the chain and der around the cassette and skewer nut. Drop the chain on the small cog, and push down.

Here's a video I made of the procedure -- no need to use your knees (?!?) or touch any drivetrain components:
http://www.youtube.com/watch?v=vxHXreuOLFM

Possible brake pad interference too.