The way I did this for a specific ordering of cards (used for a set of magic tricks called Mnemonica) was to have some sort of 1 to 1 mapping between each card and its position in the deck.
Some assorted examples: 5 : 4 of Hearts because 4 is 5 minus 1 (and the Hearts are just there). 7 : Ace of Spades because 7 is a lucky number and the Ace of Spades is a lucky card. 8 : 5 of Hearts because 5 looks a little like 8. 49 : 5 of Clubs because 4.9 is almost 5 (and the Clubs are just there).
I just memorized a deck of cards, because I was told doing so would improve my focus.
The process took 2 hours and 13 minutes, including breaks. I used 20-5 pomodoro at first, and switched to 25-5 in the middle.
I initially wrote a script to simulate a randomly shuffled deck. After memorizing the first 18 cards, I switched to a physical deck (starting with the same cards).
I chose not to use any strategy from an outside source (e.g. memory palace), because I wanted to see what I would come up with on my own, and I thought that using such a strategy might make the challenge too easy.
I began by memorizing cards in groups of four. After memorizing a group, I would go back to the previous group and see if I still remembered all of the cards in both groups. Then I would go back an arbitrarily far amount (wherever I cut the deck), and begin from there. Occasionally, I would go back to the beginning and go through the deck up to the point I had memorized to. If I messed up in an earlier group, I would repeat the process for that group.
However, after three such groups (12 cards), it became clear that four was too many to memorize at once, so I switched to groups of three. I then ran into another problem-I could memorize individual groups fairly easily, but I would have trouble remembering the order in which the groups themselves came. I was able to solve this problem by “linking” the groups together - memorizing the last card of the previous group along with the next group.
A few attributes of groups made them easier to memorize:
The easiest group was 4 of spades, 7 of spades, 8 of spades - increasing and all of the same suit.
Some of my most common mistakes were:
Sometime into the task, I grew anxious that I was wasting my time, or that it wouldn’t help, or that I should be working on something else. There were times when I felt an urge to stop and do anything else. I often get such urges when doing other activities, but this time I was able to resist them. I think that this might be because there was also a clear next step in this task, and because I knew that the point of the task was to train my focus.
About three hours after my first success, I went through the deck again, with no practice in between. I only got three of the cards wrong, though I frequently had to think for a while.
Did this activity improve my focus? I suppose we’ll have to wait and see. I was able to write this post, which isn’t something I would normally have the willpower to do, but that may have been me riding on the high of memorizing the deck (It felt so satisfying when I finally memorized the whole thing). Maybe I’ll post an update next week.