To master drawstring bags you need to master the pouch size first because you'll see how quickly they are made and then how you can change and alter them to suit your needs. This video talks you through it and makes the point of choosing some interesting wool or yarn to make your pouch/bag. You can make them different sizes for different purposes. Use at least an 8 ply wool to get stability on the sides and bottom. If you are making them very small you can use thinner wool or crochet cotton.