@handsdown In the beginning, the swelling is protective, but later it can impede the process of restoring mobility.
Coban is a stretch tape. Stretch it about 40/50% as you apply it. Start at the top, wind it towards the base, Just a small overlap, you're not trying to mummify it. Leave the tip of the finger untaped so you can check that it's not too tight.
After a couple of uses the tape loses its 'stick' so you need a new length.