I've done this several times on skin tags. But, first of all, don't do this on coloured skin tags. Those need to be seen by a professional.
What I do is make a little slipknot in a piece of cotton or silk thread, slip it over the end of pointed tweezers, then hold the tag in the tweezers, stretching it slightly away from my body. Sometimes I need another pair of hands for this. Then I slide the loop to the bottom of the tag, as close to my body as possible and tighten it. Do it quickly, because it stings/hurts. Tighten it as much as you can bear, then doubleknot. Trim off the ends of the thread to 1-2cm. Then forget about it. Don't worry about showering, swimming, etc.
At first it will look red and inflamed, then in a few days time it will shrivel and go black, then go hard and scabby and drop off, together withthe thread. Should leave nothing, just smooth skin, not even a scar (unless, perhaps, if you have dark skin). If the thread comes off, quickly tie on a fresh one. Otherwise only the top of the tag will fall off, leaving you with a little stump, and you will have to wait for it to regrow big enough to be tied off again. Tags that come off cleanly do not grow back IME.
HTH
But please, don't do any self-treatment on coloured skintage.