You'll need training from the IICRC (Institute of Inspection, Cleaning and Restoration Certification).
This is also the same place that certifies you for water restoration, mold restoration, fire and flood damage restoration ... shit like that. I've got the WRT cert ... classes are interesting and you learn a lot. Quite a bit of math involved for the average tradesman.
1: gain experience in the business working for someone else
2: look for an area with high demand and develop a business plan
3: get a loan
4: try to fill the demand through self-employment or hiring 1 or 2 people
5: experiment and improve until you have a good business model that maximizes profit
I´ve lived a pretty violent and destructive past fuelled by crack heroin and meth... And I´ve seen a lot of fucked up shit... you don´t want to clean up that mess trust me........