I've been using You know the drill regularly to expand my German vocabulary (no point in using it other than regularly, of course), and one thing that's really struck me is the power of a very simple strategy. No, not repetition. The power of repetition is amply demonstrated by regular use of the site, but I'm referring to something else. I have found that my memory of particular words is greatly enhanced if I focus on one part of the word, and connect to that. Nothing fancy, we're not talking complicated mnemonics here. Just ... labeling, I suspect. For example, versuchen means to try. I focused on "such". No particular connection between such and try, but there doesn't have to be. I simply found that, if I picked out a small part of the word, it was easier to remember next time around. Thus, in one 20-item list that I found a little harder than most, I had, among others: versuchen, verdienen, vergnügen, verletzen, verlieren. And I found my ability to remember their meanings was significantly improved when I picked out part of each word and connected that to the meaning. Thus, such-try; dien-earn; nüg-amuse; let-injure; lie-lose.
Now I didn't stare at each word as it was presented to me, and try hard to impress the association on my mind; I simply looked at the word, picked out a significant bit, and connected it to the meaning. Two seconds. And, of course, I remembered that association every time I was presented with the word on subsequent drills.
It works for me.