I know a couple tricks...
TRICK #1 -The Mind Movie -
Problem: Memorize a series of numbers 15 digits long. Series = 217136452649818
Solution: Create a movie in your mind of chronological events that incorporate all the numbers:
21 - I'm driving to the casino to play blackjack
71 - one mile over the rare 70mph speed limit
36 - one mile over the 35mph speed limit
45 - the size of my 45liter gas tank
2649 - I see two Lotto 6/49 tickets on my dashboard
818 - my cushioning of my car seats look like 818 turned sideways
When making the movie, look at the series you need to memorize, latch on to a sequence of numbers that you can anchor really well in your mind movie and proceed from there. Its best to make the movie flow so that you don't stumble into disconnects between sequences (ie. 21 to 71). So my above movie reads like this: I'm driving in my car to play blackjack (21), I take a super-quick highway (71), then I take a main street (31), I look down at my fuel gauge (45), I glance to the right to see my lottery tickets on the dashboard (2649), I look at my passenger seat to see its cushioning (818).
There is no limit to how long the story can be, its up to you. 100-200 digits is very doable. Try to make the sequences 3-5 digits long, like the (2649) sequence, that way you eat up more digits than if they are all 2 digit sequences. Also, when creating your mind movie, pick objects and places already familiar to you because they are already ingrained in your mind with no additional effort. Often I use walking through my house, going to work, or eating at my favorite restaurant because there are so many familiar objects in these places that I can easily associate number sequences with.
You'll see that after you get good at this technique, it almost seems like you are cheating at memorizing things, because it becomes to easy.
TRICK #2 -Tying multiple senses into one memory-
Problem: For some reason or the other, you always forget to lock your cottage door when you leave it
Solution: Use the environment outside of your cottage door to trigger your memory. Wait for a time when you DO lock your cottage door and try the following...
TOUCH- Take a mental note of how the door handle feels when you close it. Its curvature, its texture, its roughness, anything that you distinctly feel about the door handle when you close the door.
SMELL- Breathe in deeply. You may notice the smell of the metal door handle, the smell of the pine trees, or the humidity from the lake. Compress all these smells into one mental sensation of your cottage's exit's smell.
HEARING- Listen to the squeeling of the door handle being pulled down, the creaking of the door closing, the thump of the shut door. Sounds are extremely unique if you pay attention to them.
SEEING- Take a look at that bird feeder you see when you recoil away from the cottage door, see that distinct pine tree with its witch's back's knot in it halfway down the truck, gander at your neighbours mail box and take a mental snapshot.
TASTE- This sense comes into play very infrequently for obvious reasons so we won't touch upon it. For example, we don't usually taste our environment.
ALL TOGETHER NOW - Once you have mapped out your mental snapshots of all the sensory input you get when closing your cottage door, try thinking about them all at the same time and creating a master snapshot that includes them all. The beauty of this technique is that there are many redundant fail safes in it. For example, if your kid is yelling and you don't notice the door creaking, chances are you will still notice the shape and texture of the door handle. Conversely, if your kid is tugging on your jacket and you don't notice the shape and texture of the door handle, chances are you will still notice the smell of the pine trees, or see your neighbour's mailbox.
Often, noticing just one smell, or one sight, or one sound, etc. is enough for you to trigger your memory. Even better, is when you notice 2 at once, like if you happen to smell the pine trees at the moment you see your neighbours mailbox. When this happens, your recollection to lock the cottage door will be extra strong. DING! A light will go off in your mind and be brought to your consciousness to lock the cottage door.
The funny part is sometimes you can't turn this trick off. You could be in Germany's black forest, smell a pine tree and suddenly have the urge to lock your cottage door 5000 miles away. This is sure to give you a chuckle :) This also brings me to my final and very important point. You do not want to oversaturate your mental snapshots with too many sensory stimuli. In other words, I gave 3 examples per sense, but really 1 is enough to ensure the redundancy you need to never forget to lock the cottage door. The reason you don't want to oversaturate your mental snapshots is because if you use, let's say, the scent of a pine tree as your smell mnemonic for locking your cottage door, there's a good chance you will not be able to successfully use the smell of pine again for another memory task in the future. Therefore you always want to use the sense mnemonic that is most unique to the place you are. In the case of the cottage, the smell of the door handle is a very unique smell that is unlikely to be duplicated in any other places you will ever be.
This last notion is similar to Chroot's technique where he makes up zany stories, like a Mad scientist playing Beethoven on a person's clavicle. The zanier the story the easier to remember it. The same thing goes with your sensory mnemonic, the more unique to your given situation the less the chance of mnemonic overlap with another memory.
