The rules are stated in said subsection. But there are unwritten rules as well.
Be careful, treat the accounts you boost with respect. Most importantly, dont do anything on the accounts that can get them banned, it will severely halter, or even put you in trouble on Sythe. Stuff like raging on the account, or scripting.
That said, i wouldn't recommend anyone to boost unless theyre high diamond. If you are low diamond or even below, your orders will mostly consist of people from bronze-plat and you wont get much business from them seeing that they can get the service elsewhere from a higher rated player. Faking, or plagiarising ones rank as proof will not work either as it will sooner or later be proven fake or plagiarised, and get you banned, or for an instance once you get verified which is highly recommended to enhance your customer flow.