Here are some little tips and tricks I learned at UBI:

Cow magnets can be used to remove loose bearings from hubs.

A Park pin spanner tool can be used to hold bar tape tight before the job is finished.

When breaking and replacing a pin on a Shimano chain, the new pin should go in from the same side the old pin was pushed out from. Mark that side of the chain with a Sharpie.

To toe in brake shoes (necessary on linear pull brakes), put a folded business card under the rear 1/3 of brake shoe and tighten flat against rim.

Rubbing alcohol should be the go-to solvent for general cleaning of parts and bearings. Stronger solvents can be used if needed. Never soak a chain, as that removes the internal grease which can't be easily replaced.

If removing bars to work on headset, strap the bars to the bike with a toe strap.

Little things that don't really matter but indicate professionalism: hub labels readable while sitting on bike (and through the valve hole), tire label at valve stem and on drive side, bar wraps are mirror image R/L, bar plugs with upright graphics, headset cup logos lined up.