Use a 50:50 mix of perlite and multi-purpose compost. The plant will not need much food, drainage and support and more important.
Choose a healthy stem and cut below a node. Preferably a non-flowering stem, otherways cut the flower out.
Take this cutting and remove one of the leaves - so the plant has less to keep alive and can concentrate on rooting
Dip the cutting in hormonal rooting powder with a fungicide
Firm the cutting in, so that it will be well supported by the compost but have access to plenty of air within the perlite/compost mixture
You can fit 2 or 3 in a pot, make sure the leaves are not touching as this may cause them to rot
Seal them inside a plastic bag with an elastic bag and water from the bottom - here they have capillary matting in the greenhouse, but an occasional saucer of water would also do the job - they will not lose too much moisture because of the plastic bag, so don't overwater - rot is the main enemy!
Take the bag off once they are rooted, they will then grow away incredibly quickly.