For assembly:
There's a
tool for making sure the extractor rod is torqued down. New guns are usually fine. Used guns if it's ever been loosened it will eventually unscrew. Not guaranteed, but it usually will. If the knurled end of the rod is marred then someone took a pair of pliers and did a half ass job. Torque it down properly. I don't think there's a ft/lbs rating. Just by feel. It doesn't take much when using the correct tool.
After that I button it back up and make sure like LSP972 says all the screws are properly fastened. On the new guns you can actually get away with a Brownells 150-3 bit for most everything (sideplate, strain, thumbpiece screws). At least on the 686s and 627 I've been in recently.
For a single user doing maintenance on a single gun (or a few) It's
mostly user error beyond that point. There are armorers here that can go into detail about supporting an entire fleet.
For ammo:
Clean ammo solves a lot of problems.
For shooting:
Cleaning is a pain, so I only brushed out the chambers and cylinder face before a match. My standard load was 4.7gr New Unique with a 158gr lead bullet, which chrono'd somewhere in the 800s. That was a big enough charge of Unique to not leave flakes of powder everywhere.
Safariland Comp 3 speedloaders are disposable. Drop them in the dirt often enough and eventually the activation button will get sticky. They still work, but can get sluggish. Other shooters have managed to never have this happen, but I've thrown away used-to-work Comp 3s that eventually started giving spotty cartridge release.