I take a picture of every snake showing the dorsal pattern~ print it on a 4X6 card, put all the info for that snake such as hets, parentage, if I bred it or purchased it, who I purchased it from, contact info for the seller, purchase price~ basically everything on that card. Then I label that card with a number showing the type of snake BP for Ball Python or C for Corn snake, the year I made the card (which is the year I obtained the snake~ could be it's birth year or it could be the year I purchased it) and an individual snake number beginning with 01 at the beginning of each year. Such as~ the 23rd baby hatched last year is
BP-08-23
But the pied Heather produced and sent to me came in after all my babies had hatched~ she is
BP-08-58

I put all those cards into a file box~ put a sticker with the snakes number on the snakes tub, take another 4X6 card and write the snakes number ontop of it. I hang the new card on the front of the rack in front of the snakes tub and mark down feedings/shed/breedings/eggs~ whatever~ on that card. As each feed card fills up I file it in the box behind the 4X6 ID card for that snake. Before I sell a snake~ or if I ever worry I've put someone away in the wrong place I pull that snakes ID card and compare the picture taken as soon as I got the snake (or right after hatch) to the snake to ensure it IS the correctly IDed snake.

Sounds more complicated than it is. Making the ID cards is a pain~ but once they are made~ it's easy to keep track and double check that no one gets mis-IDed