Dry fire - keep it to a minimum
Half pulls - not a good idea, can lead to where your mechbox is locked up. Typically it doesn't "break" anything...but rather sets the spring in a compressed state such that a weak/worn/old motor can't grunt it over (torque) to start the firing cycle. Might not be a problem with a new setup...but after time it's more probable.
Rain - typical game play...no. Submerging an electrical toy...not great. Aside from the battery/wiring/motor...you need to be aware of rusting (if you care about that). Iron/steel rusts...pot metal and aluminum doesn't...set screws will typically rust and can seize. Also...rain/water plays havok with BB's as they become very inconsistent (i.e. wet BB's pick up completely random amounts of hopup...and a wet inner barrel will toss shots way off). Use your head when playing in the rain. Swab out the barrel when you need to. DON'T leave a wet gun packed away in a hard case for days after a monsoon of a game.....any metal bits will rust, your case will smell funky, you'll have mineral deposits (like with a glass of water if you leave it out and all the water evaporates) in your barrel that you'll have to scrub out)....trust me on this one
Other general stuff....
- keep all the screws, nuts, pieces of your stuff snugged down....either check it regularly or use loctite
- metal bushings + reshimming can greatly prolong the life of your mechbox
- low voltage batteries + low power springs (i.e. 300-350fps) = long time fun
- if it ain't broke...it's worth a once over, but don't "fix" it
- use quality BBs (e.g. BBBastard)
- use quality batteries (e.g. Intellect, GP, Sanyo)...avoid the cheap crappy green/black no-name stuff.
- get a good smart charger...might seem expensive at first, but it pays for itself over and over and over
- no petroleum based lubricants...or lubricants with a petroleum carrier. Thicker silicone oil stays in place longer than really lightweight stuff....but attracts dust.
- DON'T spooge oil/grease into your mechbox...it doesn't need regular lubrication "top-ups". Just lightly grease it when assembling and that's enough until the next time you take it apart. What's in there will stay in there.
ALWAYS clear your AEG when you're done or BEFORE going into the safe zone...since it's battery powered and you can't see the chamber you MUST do the following in this order:
1. Remove magazine/source of BBs
2. Invert (typically) the rifle so the feed tube will "gravity feed" any BBs left in the feed tube/hopup
3. Point in a safe direction...you're not in game play...so pointing anywhere but a safe direction is just ass lazy and ignorant.
4. Fire on SEMI...keep firing until you get at least 3 blank shots
5. Put it on Safe
6. Cover the muzzle
7. Don't fiddle with it
All the above (and a lot more detail about everything) is buried somewhere in this forum...search/troll/read more.