Never, ever use tire levers to install a tire.

Cut brake cable housing as short as possible--no loops, thank you very much.

After applying oil to a chain and pedaling/shifting it a few times--WIPE IT ALL OFF!

Never patch a tube--it's a waste of time. Just buy a new one.

Turn all cable adjusters in before installing new cables.

Tape bars from the bottom to the top.

Use a bike stand.

Use the right tool for the job.

When the bike is in the stand, turn the pedals by with your right hand and manually attempt to push the rear derailleur into the spokes with your left hand to check the limit screw adjustment.

When checking headset tightness, don't squeeze both brake levers when rocking the bike back and forth. Just squeeze the front one.