Usually the first things to fail, on outdoor gear, is the zipper. I worked at an outdoor store that was next to an awning shop. Often times people would bring in tents that needed zippers replaced and we would send them next door. After a while, the owners of the awning shop recommended that we offered cans of silicon spray with the purchase of a tent. The theory is that silicon coats the zippers making them slide easier. Silicon also makes it so the dirt will be less likely to stick to the zippers, effectively extending the life of the zipper.
1. Clean all zippers ensuring they are free of dirt.
I have found the best way to do this is with a regular spray bottle. On a hot sunny day spray the zipper with regular water and then let dry.
2. Spray zippers from both inside and out with silicon spray.
3. Let dry for several hours.
Spray the rest of your outdoor equipment zippers.
If you use your tent a lot, you may want to repeat this procedure every 6 weeks. If you only use it a couple times a year, you should do this before the first use of the season. I would recommend doing this to any outdoor gear that has zippers.