Welcome to the forum,
As a professional, you want bulk packaged products that get the job done at a low price to keep overhead low.
www.autoint.com offers bulk products that get the job done with no frills and fancy packaging. They can also give you advise. The detailing manual is a good buy to get you started in the professional world.
What products you need will vary form car to car. What application method are you aiming for? Hand, polisher, or rotary?
Exterior
A car wash
An automotive de-contamination system.
Polishes from several different levels of abrasiveness
Wheel cleaner
Tire cleaner
A rotary (experienced users only), or a orbital polisher for applying the polishes/cleaner waxes.
If you want to speed removal an orbital outfitted with a microfiber bonnet or terry bonnet.
Tire dressing
Trim dressing
Glass cleaner
A wax product and maybe offer a more expensive sealant.
Maybe have a quick spray wax option after a wash or soemthing.
Of course have towels, applicators, and pads.
For the Interior
A commercial wet/dry vac, blower.
Extractor
Steam Cleaner
Ozone machine (gets rid of odors.)
A vinyl cleaner.
A vinyl/rubber dressing.
Carpet shampoo.
Also
www.topoftheline.com www.prowax.com offer professional details products.