What else do you do besides memrising to help the new vocabulary stick?
From my personal experience, I cannot emphasise enough how immensely helpful it is to read extensively from an early a stage as possible. Basically from the get-go, if the language is not too different from ones you know already (which was the case with me, but I don’t know what languages you are learning).
My language journey with memrise has been part of an experiment to learn languages in a less “schooly” way: no textbooks, no grammar books, no language-learning courses of any kind, using materials I enjoy, oh, and the minimum of cash spent 
So I got hold of crime fiction in my target languages (first Swedish, now Dutch added in the mix) because I enjoy reading crime fiction (obviously, each individual has to find something that they personally enjoy and find stimulating and interesting). Initially, I also purchased - second-hand - translation(s) of the books I was reading and read them alongside one another.
Seeing the words in context, realising that they also had different translations than the ones I was familiar with, writing them down on paper or in digital form (having a new mobile phone with google docs was a godsend) and later adding the new phrases as mems to my courses, all of this helped the words to really stick in my head.
For some reason (and it may make me a good language learner, apparently, from what I have read about the subject), I seem to learn words better if I can embed them in phrases and then learn the phrase (fixed expression, lexical chunk, call it what you will) with the new word inside it, so to speak.
And the only way to expose yourself to a large number of phrases in a way that really sticks in your mind is to read. Steve Kauffmann, a Canadian who set up the company “LinQ”, is a firm believer in the power of reading, and I can only confirm what he says. He seems to believe that the act of reading taxes the brain to a greater degree than, say, watching a film. Watching a film or a video clip is what we do to reward ourselves for our hard work reading, he says, but it is not the best way to actively learn new vocabulary and phrases.
It makes the reading that much more enjoyable when you see a word you have just learnt in context and you find yourself going (or at least, I do!), “Oh, I know that word, that means “X”!”. It makes the whole process of learning the vocabulary in the first place more rewarding when you realise you are learning words that are actually used
Oh, and picking up everyday phrases is easier when you read a book with a lot of dialogue in it. I have just learnt, for example (@richardmtl) that Dutch people say, “With John Smith” (in Dutch, natch) meaning, “John Smith speaking” or “John Smith here” when they initiate a telephone call. I was so surprised to read that, but now I know why there seems to be so many words for “with” in Dutch: one of them at least has this special usage. This is the kind of thing that you don’t generally learn on memrise courses, which is why reading complements vocabulary learning so well.
