Hi and welcome to Clea It Up
I would start with training.
There are number of course, some are linked to a manufacturer of cleaning products so you would expect a bias, but they get spoken well of.
An independant trainng is via the National Carpet Cleaners Association
www.ncca.co.ukgo to their website and click on the "training" button.
there is a course starting a week on Friday for 2 days (fri & sat)
then next one is in April.
you will get the chance to try different systems as well as being taught by 2 top notch carpet cleaners.