Azura
What is it you have been asked to clean? A house, Offices etc etc??
I personally would not recommend the "hire a machine and see what happens" approach.
Being an ex-carpet cleaner, I know the dangers of carpet cleaning and how easy the carpet can be damaged, ruined etc in the hands of those who do not know what they are doing. Fine if doing your home carpet....but someone else's carpet....!!! Could be very expensive. Know of someone who cleaned three floors on huge office block....nice tiled carpets when started....next day a dirty brown colour, ruined carpet tiles and a bill for £70,000 to replace the whole lot!!
You will want to get three or four quotes from professional carpet cleaners and see what they will come up with price wise...make sure they do a thorough site survey and qualify the job to you.
Failing that, go on a carpet cleaning course yourself i.e Prochem, buy a machine, do it yourself and incorporate an annual carpet cleaning service into the contract you are going for, plus you will be able to provide the service elsewhere and make lots more money.
Anyway, don't wish to frighten you on your first quote....but you need to be aware of pitfalls as you go.
All the best on this and hope you get it.
Tim