Ninja Stack
A gentle way into memorised-deck work: a random-looking stack that tells you both every card and its position.
A memorised deck is one of the most powerful things you can carry, and most magicians never get one, because learning a stack looks like months of work.
Ninja Stack is the one I’d teach you first. It’s cyclical and it looks random, so you can recall not just the order but each card’s number in the deck — and you’ll be using it within a few hours, deck in hand, as you watch.
In the hour and three quarters you’ll also learn weighing the cards, dead cutting to a named card, and a very clean ACAAN. There’s a bit of thinking to do at the start, and the ACAAN asks for a little arithmetic, but nothing punishing. If you only ever learn one stack, I’d make it this one.