Here's a great method I read about on JMPP:
Take a regular 8 1/2 x 11 piece of blank paper and hold it horizontally. Fold it in half so that you now have an 8 1/2 x 5 1/2 surface. Then fold it again (same direction) so that it is in quarters, then again so that it is in eights, and then unfold it. You will have a piece of paper with 8 narrow columns. Across the top of the first column write "English," across the top of the second write "Spanish," then "English" atop the third, and so on.
Take about 25 vocab words (depending on how big you write) that you want to learn, and write them down the side of the first column in English. Then write their Spanish translations alongside them in the second column.
Now fold the 1st column (English) underneath the rest of the page so you can't see it. You will be left with a column of 25 Spanish words and a blank column in which you are to write their corresponding English translations (you'll also have five other blank columns). When done, check your work and make corrections as needed. Then fold the two left-hand columns (already written in) underneath the paper so that you have an English list for which you need to write the Spanish translations. Repeat this until you get to the last column and I'll bet you have all 25 memorized.
Heck, it may even work for memorizing vocab from chem, bio, etc. Seriously good idea. I'll have to try this sometime.