Check out the photo, it should be pretty self-explanatory.
I’ve found the best technique is to cut/tear a strip of 4-5cm wide strip of paper towel, fold it lengthwise a few times, then tie it around the neck of the bottle. (You can trim off the ends if you want – I can’t be bothered).
I’ve also tried securing the paper towel with a rubber band – this works ok for sauces, but oil degrades the rubber band and it breaks within a few weeks. Sticky tape has the same problem.