What i need to get/need before i buy a horse...?

Basically, my dad said that i need to prove to him that i will commute to getting a horse and like show him that i would be preaperd to getting a horse... money is the big thing he thinks it will cost wayy to much true but ive said i will get a job ... ive been riding since i was 2. basically all im asking is for you to give me ideas on what i need to like get and what i need to find like farriers etc. also what i can do to persuade him. thankyouu :)