As wool is a primary and popularly used fabric for base layers, it is appropriate to address a question specifically about it. The reality is, there are extra precautions you can take to ensure that your wool garment lasts as long as you want it to. These types of base layers are not the cheapest, so you want to do everything in your power to ensure their shelf life.
Firstly, when dealing with stains be sure to rinse them off with cold water and then a dry cloth. After you get done washing it, to remove the excess water, you can roll it up in a towel. Then, you can proceed to air dry it. Never air dry it with direct access to the sunlight, even with a UPF rating against ultraviolet rays, it is still not recommended to do so. If your base layer happens to be incredibly wrinkly, instead of ironing it you should hang it up in a steamy bathroom. Finally, it is not a bad idea to have it dry cleaned once a year.