Getting paid
To be paid then you must hold a CPL of some sort. To charge for 'Public Transport' or 'Arial Work' (Instructing) you must hold a valid 'AOC for that purpose.
If the Pilot is both a CPL and an Instructor for the purpose and both of you, the Instructor and Student, are members of the same club then the instruction (Arial Work) for payment is exempt the AOC requirement. To instruct for any licence or rating you must be a 'Registered Training Facility'.
Only the 'sole owner' or spouse/children may train on an aircraft with a 'Private Cof A', for the issue of a licence or rating. The Instructor in this case should ensure that within the owners insurance policy the Instructor will benefit as a third party to any accident ('.....Hold Harmless .....' clause).
To carry on a business involving the public you must have Public Liabilty Insurance and also Employers Liabilty if you have any sense.
Most owners who approach an individual Instructor to train them do so to get it cheap and to avoid the costs that otherwise must be met. I know of one Instructor who 'moonlighted' from his club and trained on a private aircraft. During one such sortie the aircraft struck trees following an EFATO. The insurance paid for the aircraft to be rebuilt and compensated the owner for his injuries. The Instructor is lame for life and requires a walking stick - didn't get a penny!