Cut yourself two cardboard 'donuts'. The bigger the donuts, the bigger your pom-pom will be. In particular, the bigger the hole in the centre the bigger and fluffier your pom-pom will be (but it will take more fabric.) Mine was about 30cm across.
Choose your fabrics and cut them into strips. The strips can be any length (and width) but if they're very short you may want to knot them together to make longer strips. I used a limited palette of colours but you could go for a rainbow style or just use a single colour. I used a range of materials too; ribbon, trims, fabrics, old clothes. Try anything!
Place your two donuts together and start wrapping the strips of fabric round and round. You're basically going to keep going round and round and round and round and round until the hole in the centre is filled in.
Now for the difficult(ish) bit. Once the hole in the centre is filled you're going to start cutting around the edge, right down to the cardboard. You should have used a fair amount of fabric so this may take some time. You'll end up with the two cardboard discs showing and lots of fabric bits hanging down on either side.
Take some strong thread and tie the pom -pom off by tying it round the middle, between your cardboard donuts. Tie it as tightly as you possibly can and then rip off the cardboard. You can then trim any straggly or uneven bits and fluff up your pom pom. Done!