Flash cards were crucial for my studying in dental school. Handwritten cards are way too time-consuming to make, though. They're easy to make on a computer if you just set up a template in Word and use that template every time you need to make a set. Set the margins to narrow, .5" on every side. Set the paper size to 3x5" (index card) setting. Odd pages on your word document will be side 1 of your flash cards, even pages will be the flip side. Save the template document to your desktop or somewhere handy, and then open it and save under a different name once you start putting flash card info into it. This way you won't have to waste time setting it up every time.
Just buy a bunch of 3x5 cards, feed them straight into your printer, print out the odd pages. Flip the cards and repeat for even pages. I've found that Lexmark printers have the best feeding mechanisms, meaning they almost never double feed a card. Even the cheapest Lexmark printer at Wal-Mart will do the job. Print 25 or so cards at a time so you can make sure they aren't double feeding.
People always gawked at my stacks of hundreds of flash cards, but hey, they worked great for me. I didn't use them for every class, but sometimes they worked perfectly, especially when I had to memorize a bunch of old test questions for short answer tests.