The truth is, it varies from person to person. Some people like to get all colourful with their learning - they find that using differently coloured pens or differently coloured flashcards and notepads help to stick whatever they're learning in their mind. For others, repetition is key - just simply going over and over a verb table or a tense can do the job. What I found that worked for me is learning about the individual words themselves - learning the etymology or cognates of verbs and verb endings, I find, really facilitates mass-learning as each word begins to stand apart from the others; you really begin not just to know what you're trying to memorise, but you also begin to understand and appreciate the words themselves, making them stick out more, and easier to remember as a result.