Division is easy to do; when a clump has more than one "crown" or rosette growing from the base (provided that each crown has formed its own roots, which you should see if you look closely or brush away a bit of soil), simply lift out the plant and slice the two crowns apart neatly with a knife or gently pull them apart by hand. A cutting would involve slicing off a crown piece that does not yet have roots, and then sticking it into a moist medium and keeping it humid until it forms roots of its own. This is tricker than division because the crown may rot before roots form. For the easiest and least invasive method of propagation, you can peg down the runners that are sent out horizontally, and when the new plantlet at the end of the runner sets down roots of its own, simply sever it from the mother plant and transplant as you like. Usually the runners will root without any help from humans, so it isn't even necessary to peg the runners down unless you're really in a hurry to move things along.

Take care!
Stefan