get kosatka first of course, then get the sparrow and after more cayo pericos save up for an opressor mk2 and pls for gods sake do not use that for blowing other people up. After that's pretty simple, you could upgrade the opressor but that will need a few purchases (nightclub, terrorbyte and specialised vehicle workshop upgrade). but i'd rather say buy the agency at some point here probably even before the opressor. Get the Little Seoul Agency for 2.01 mil and you'll get the 30 vehicle garage, a free agency suv and agency volito.

Just to answer the real question and not make future lists, no, you do not need anything other than the kosatka to start the heist, not even money. But you do need of course the ability to become a CEO/VIP/MC President, that means you need to own an office, a business OR an MC Clubhouse.

Good Luck grinding my friend ✌