(3) should be impractical Only thing I can suggest for learning prefixes is to read and speak as much as you can. Practice, practice, practice ! :) If reading is too difficult, find a conversation partner in English. Over time you will assimilate the correct prefix without thinking about it. Rather than thinking about "what prefix to use", you start to use the correct word without thinking about it. When you're speaking, don't be afraid to make a mistake. For instance, "un" often prefixes a word for it's negation. Like the word "unavailable". If you don't know the correct prefix for the negation just try that. For instance you want to say "illegal" but don't know to prefix it with "il". You could say "unlegal". A lot of grammarians may hate this, but as a native speaker I would still understand you and correct you. Edit: Flashcards are a handy way of memorizing words as well, if you haven't tried that. Put the word on one side and the same word with the prefix you want on the other. Quizlet is one free tool. There's plenty of others.