What's the best way to learn vocabulary?

Either putting them on post it notes and sticking them around your room so you see them everywhere or making flashcards with the English word on one side and the French word on the other. There are loads of apps you can get as well which can help with this (Quizlet is my favourite). The key thing is not to leave it too late and try to cram vocabulary, you need to be doing little and often (maybe try 10-15 words a day) and keep refreshing your memory. Another idea for picking up new vocab is try to read the news/magazines/even books in French and just picking out the words you don't know. You'll start to see a big improvement in a couple of weeks!