Serious percussionists know that gaffers tape can be an invaluable tool when it comes to improving drum sound. Used carefully, and in small increments, cloth gaffers tape can change the tone of individual drums just enough to make a kit sound really cohesive.
Use too much or use it in the wrong places and it can make the drum sound worse and leave a real mess when you try to remove it.
The secret is to use small pieces and to work slowly from the outside edge of the drum head towards the center as you carefully listen to the drum.
Ideally, the tape should be applied in such a way as the drummer will not hit it directly with a stick, as your goal is to change the tone of the drum, not change the impact the stick has when the drum head is struck.
Here’s a link to a really useful video which explains the process in detail.