The easiest way to memorize preflop charts is to not memorize them.
Ok, but seriously, if you have to memorize it, the easiest way would be to start at one row, diagonal or column at a time. I would recommend you “memorize” the general shape of it more, but if I HAD to memorize the specific combinations, that’s what I’d do.
For example, this is some random preflop chart I found on Red Chip Poker, but if you imagine, there’s one for every single position, trying to just look at the overall graph, memorize it, and then move onto the next one is going to confuse the crap out of you.
Instead, here’s what I would do.
I would look at every single position – so for example, I would look at early position, middle position, highjack, cutoff, button so on and so on. And then I would first go row by row.
First look at the suited aces row for every single position. You’ll find in a 100bb cash game, every single position with some frequency is opening every single suited aces. Ok cool, now let’s move on. How about suited kings? Usually from early to mid position, you open starting from K5s+ with variable frequency and then in late position to blinds you’re doing K3s/K2s+.
Using this process, I would go down the rows. And then move onto the suited connectors and so on.
Trying to memorize an entire graph. Then move onto the next position, and memorize that graph. And then the next. And then the next will give you a headache.