There are two main reasons to change the skins on your drums: the first may be because you bought a new drum set, maybe your first, and you want to immediately put on better skins; the second reason is simply because the old skins have worn out and it's time to replace them.
But when should you replace the skins? Skins can be replaced when they have aged and may have lost elasticity, or – in the case of the snare – when the coating starts to come off. Sometimes the skins tear, as can happen with the bass drum, or small indentations can occur due to the impact of the drumsticks.
The skins can be sandblasted or transparent, and the choice depends on the type of sound you want to achieve. Also, when you change the skins you need to stretch them and tune them properly. If you’ve never done it, it’s advisable to get help from someone more experienced.
Regarding skins, it’s good to always have some replacements on hand because you might find tears or lesions at the worst possible moment, such as right before a live performance when it’s too late to buy another skin and replace it.