When I'm learning German words, I keep a notebook where I write words and I make spider-web charts of related and derived words. I'm a highly visual learner, so writing, drawing, and using different colours helps me remember things. It also helps me greatly to make charts of words relating to the same topic -- I arrange them visually in a way that helps me remember.
I also use index cards to write down words with relevant information on the back: definitions, synonyms, etc.
I then try to recall some words when I'm doing my everyday things -- when I'm shopping for groceries, I can try to name things I'm buying in German, etc.
I think the most important thing is to learn what kind of learner are you -- visual, auditory, or kinesthetic. There are simple questionnaires that can help you figure it out. Then find out ways that will help you learn using your optimal learning style.
Hope this helps somebody.
Student or Learner