this is how i would go about it, others may have different ways....
have a well drained compost at hand, or mix in perlite with multipurpose.
choose a shoot that has grown this summer, ie. one that is not all woody and hard. i would have the cutting legnth at 4 inches or so.
i'd cut under a pair of leaves, remove bottom leaves use hormone rooting powder if you choose, and pop into the compost, round the edge of the pot. cover with plastic bag or place in propagator with some bottom heat.
if you're taking cutting from slightly older (woodier) part of plant, i think the idea is to have a cutting with a 'heel', which means you don't cut sharply under a node or pair of leaves as you normally would, but slightly 'snap' the cutting so a little bit of the stem comes away. pot up as above.
didn't explain the heel bit very well, :(perhaps others could do better......