[ujiro]

You hit the major points right there. Re-check shimming, ensure no issues with bearings/gears, and regrease and relube everything. And cleaning the barrel and inspecting hop up for any issues/ checking the rubber. Those are the basic things I do on every takedown. I would check your compression as well, by seeing if the piston head makes a good seal with the cylinder. Other than that, if the gun is running smoothly, don't touch anything else. Nothing else really needs any work.
Oh the one other thing to check would be the switch contacts. Just see if any scorch marks are showing up from the electrical arc across it every time you pull the trigger. if there are any, just scrape them off.

Read Skladfins post below.
I agree. I don't take it apart after every game, I don't relube it after every game. I relube it after maybe 5-10 games, or once a month.
I clean the barrel and hop up/rubber after every game though. Like he said below, easiest way to keep your gun consistent and accurate between games.