Mnemonic techniques are no great mystery. There are only four basic ones, they are all ancient, and information on them is available from many sources. They are: (1) Chaining, (2) Peg Memory, (3) The Number Alphabet, (4) The Mental Journey aka House Of Many Rooms aka Associated Location.
Chaining has to do with simply associating each item in a list with the next. It is trivial and of very limited use, and if you can’t remember one link all successive links may be lost. Peg Memory is about taking a list that is easy to remember and placing it in one-to-one correspendence with the items you want to remember, using the principles of association. It is fine for one list of items, but that’s all.
Number Alphabet is about converting numerical information into words using a simple conversion system. It is very powerful, and has many applications.
Mental Journey is a special and extended refinement of the Chaining and Peg Memory systems, except that it is literally infinite in capacity. It involves preparing a sequence such as a list of 50 locations on a journey you can mentally walk through (preferably based on real life experiences and memories), and associating each item to be memorised with one ‘stop’ on the journey. You can remember as many items as there are on the ‘journeys’ you make up.
When eight times World Memory Champion Dominic O’Brien wants to memorise 36 shuffled decks of cards, he prepares 36 journeys of 26 locations (he associates two cards at a time with each location).
The principles of association are easy to summarise: associate one mental picture with another. The more colourful, exaggerated, imaginative, active, big, bright, dramatic and fun the images are, the better your retention will be.
None of these techniques really lend themselves to acquiring language vocabulary, unfortunately. What’s more, if Steven Pinker is right, then from the age of 0 - 5 the brain is ‘wired’ to devote a large percentage of resources to language acquisition, but after that the ‘language acquisition’ circuits diminish a lot, and the brain starts devoting resources to other tasks. This is why it’s very easy to learn a language as a child, harder as an adult.
All that having been said, here are the only techniques I know of that might help.
(1) Imagery. Your sub-conscious mind understands and can process images, but cannot process words or semantic data. Try where possible to deal in images to form memory associations. To remember that ‘window’ is ‘fenetre’ in French, form a mental image of a window and look through it to see an big iron (Fe) net = fenet. This doesn’t give you the whole word, but it jogs your memory and gives you a clue towards fenetre. Use the principles of association to make the mental images as memorable as possible. (I know there should be an accent over ‘fenetre’, but I can’t be bothered to type it correctly.)
(2) Gap Principle. If you want to learn something new, first of all focus on the information once an hour. When this begins to feel redundant, refresh it three times a day - morning, noon and evening. When this begins to feel redundant, refresh once a day. Then three times a week. Then once per week, then finally once per month. The actual gaps between refresh will vary according to your needs and schedule, but you get the idea. Start with a frequent refresh schedule, and gradually extend the gaps.
(3) Super Memo. See if any of the techniques on this site help. In particular, the Super Memo took might help - it’s software that uses the Gap Principle (see above) to help you learn things.
(4) Consistency. Try to train your mind to associate certain times and stimuli with learning and absorbing information. For example, say that you will spend half an hour on memorisation tasks, always at the same desk, at 10 am, with a Musk Oil incense stick lit, with a glass of orange juice to sip, and a Chopin nocturne playing very quietly in the background. Obviously, you vary the specifics to suit yourself. The point is to try and train your mind to associate this very specific combination of sensory stimuli with new learning and new memories.
(5) Dawn Principle. Try to do your memorisation as early in the day as you can. When you sleep, your brain sorts through all the inputs of the day, moves some stuff into long-term memory (LTM), clears out the short-term memory (STM) and is ready for a new day. So when you wake up, that’s when your STM cleaned out, receptive and ready for new information. However, STM doesn’t last more than a few hours. So, whatever you put into STM early in the day, you need to refresh later in the day and in the evenings, so your mind knows this stuff is important and needs to be moved to LTM overnight.
(6) 2 Way Street. Be sure to learn associations both ways. Let’s say you have two lists, List A with all the English words and List B with all the corresponding French words. Half the time go throuhg List A trying to remember the French equivalents, and half the time go in the other direction. This is many times more effective than only ever trying to go in one direction.
(7) Sense Totality. Use all your senses. If possible, don’t just read the word. SEE its written shape, HEAR what it sounds like, TRACE the word shape with your finger as you SAY it. The more bits of your brain circuitry you can make light up, the better your chances of remembering.
(8) Fitness. Fitness, health and sleep are all things we should take good care of anyway, but they all have a bearing on memorisation. The fitter you are, the more good sleep you get, the more healthy you are in terms of your diet and hydration, the better your chances of remembering. Dominic O’Brien (see above) embarked on a three month progra of jogging and fitness as part of his warm-up for each World Memory Championship contest.