Try them out
Find some professional detail supply companies, and see what all their products do.
Memorize at least 10 different lines of polishes, glazes, waxes, and compounds. Pick your favorite 3 or 4, and order a different kind of each, one polish, one glaze, wax, and compound... Do some details for friends for nearly free, take your time, test.
Then when they get about half way empty, buy a different brand of each version, and repeat... You can start charging full prices when you're turning out professional results every time without spending 12 hours
For interiors, get very proficient with a vaccum, terry towels, microfiber, and spray carpet cleaner... Get a Bissel Little Green Machine, with heat. Then you can sort-of extract carpets... Until you can get one of those $700 ones!
Practice lots, you need a lot of experience and "references" to detail for money. And legal issues should be top priority as well. As soon as it turns from practice on friends to making business cards/flyers, licenses are needed.