Tried my hand at playing the engineer, and I learned I'm terrible with the little Texan mechanic. Ya'll got any tips for this poor old guy that just wants to join in on the fun?
Heres a bunch of various tips, most of them fairly obvious if you've been playing a while.
Watch out for where other people place sentries while playing as other classes, the more common locations are usually good places for you to build.
If another engineer has a sentry covering one entry into an area, try setting up to cover a different entry/area the enemy can use to target the other sentry.
In most cases building right near another engineers buildings is just asking for a single demo/uber to take them all out in one go, don't do it.
If a spy saps your buildings when no one else is around, switch to shotgun and give him several blasts then swap back to wrench to kill the sappers.
If you can see other teammates taking on the spy, then concentrate on killing the sappers.
Once a round starts try to keep above 40 or so metal while you are upgrading your buildings, as this gives you a reserve to repair them when an enemy arrives.
Once your buildings are fully upgraded/while waiting for metal to respawn, use your shotgun to spycheck everybody.
Remember the only people who can stand on buildings from your side are the engie who built it and enemy spys. If you see someone doing so, spycheck them.
Work with other engineers to get one sentry to level 3 fast rather than two partially upgraded level 1's.
Similarly, if your gear is already upgraded then help a nearby engie upgrade his stuff.
Be aware of other engies gear, particularly if they have been sapped so you can repair/kill sappers if the other engie has been killed, saving the gear.