A wet tent left in the hot trunk of your car can be ruined in a matter of days. If possible set up your tent in the shade, or take it down during midday to avoid UV damage. Most quality tents are made from fabrics with UV inhibitors, but these fabrics are still highly susceptible to UV damage. If you set up your tent at high altitude or in the snow for an extended period of a week or two or more, be aware that you are decreasing the life of your tent dramatically. A tent set up in your back yard for the summer will die a slow death.
Himalayan expeditions can kill a tent in two months.
Always, always, always anchor your tent to the ground. Campers with freestanding tents frequently neglect to do this, yet just a light breeze can blow your tent over, even when full of gear, causing damage or complete loss. Be extremely delicate when shoveling snow from around your tent. Your tent fabric is light weight and easily damaged by sharp shovel edges, ski poles, ice axes, and the like. Zipper sliders can wear out unbelievably fast in windy, sandy campsites.