I'd echo all of the above. One pretty important issue is proper post-dive rinsing, Ever notice the "griminess" and stickiness of something that has been in salt water, and not rinsed? That's most likely the salt crystals forming (ever seen the piles of salt in Bonaire? - they come from sea-water...). Well, those very salt crystals are pretty angular, and cause undue wear-and-tear on relatively soft things like seals. Worse, they can also "bridge" between the housing seat and the control surface. So a suggestion would be to soak your housing post-dive, and also resist (IMHO) the temptation between dives to see if you got the shot, unless you've had the housing in the rinse tank.
Most of the mfr's also talk about valve seat maintenance. Most suggest the soaking routine, too. As for the main seals, etc., try to store your housing in a cool, dry place, as heat is a big enemy.
As for the main door seals, they simply have to fit. I don't store my housing with the port or door seals installed. I carefully remove them, clean them, then put in a plastic bag. When re-installing, I take a Q-tip swab to the groove, and make sure it's cleaned out. Now with my old eyes, I even take a magnifier to the groove, to make sure I got all the junk out. If you do a lot of muck diving, you'll often have your housing on the sand, and the grooves are really good at picking up sand/dirt in the grooves.
Edited by dpaustex, 14 May 2014 - 12:39 PM.