The silicon is a lubricant for the o-rings. Use just enough to give the o-ring a bit of surface gloss. It`s to keep the ring from wearing and drying out. Properly maintained o-rings can last for years. It is best to remove them for long term storage just keep them in a clean plastic bag. The only other thing to worry about is keeping everthing clean and inside the housing dry. A single speck of dust, a hair or eyelash in the o-ring groove or on the o-ring can and in most cases will case a leak. Using silcon desicant packs or moisture munchers in the housing will keep the insides dry. Finally rinse the entire rig with plenty of fresh water after each dive.