The best source for vocab aquisition is Latin works, actually.
Read, read, read; that's the best way to memorize words naturally. You don't have to actively memorize them; they get memorized of their own accord. You'll come across a word once, maybe twice, maybe thrice or maybe even more and forget it, but if it's one that often recurs (i.e. if it's a common word and therefore most necessary to know) it will eventually stick. If it's a rare one, it may also stick owing to being striking one way or other. That way you also get to see words used in context, which will enable you to become familar with their various meanings and usages. That doesn't quite happen when you memorize a list of words with only their basic meanings (though doing the latter may be necessary at some point in the very early stages of language learning, just to acquire a few most basic words for starters).
