I would add a few things I learned to improve your memory:
1. Care about the subject
2. Focus on memorizing it: This may seem dumb, but how many times have you forgot where you placed your keys? If all you do is momentarily state to yourself "I set my keys here" when you put them down, it's almost hard to forget.
3. Don't eat white sugar or white flour processed, or other foods that may cause you to loose concentration. (I tested this theory when trying to memorize stuff. Crazy the effect it has)
4. Associate a picture (with an action or something outlandish) with the item. You can take a list of 20 items where most people get only a max of around 4 items, I can memorize the entire thing by making a story with the items. No practice needed, it works the first time for most people. Works for memorizing directions as well. (too long to explain the entire process in a comment)
These are just shortcuts though... (from a few memory courses I took in the past)
Also another trick (without going full formaliser spaced repetition): reread the same thing the next day, and then a week after. Boring but very effective for long term retention.
I would argue you better practice recall than rereading, i.e. put some notes after reading, make an abstract, expand on it with new thoughts next day, in a week etc.
Just rereading might be a) boring b) constantly giving you a sense of familiarity, which is not knowledge.
When I have to reread something that is not too deep I sense that I have made a mistake first time by not really thinking about the text.
I've always been confused by people talking about losing things like keys/wallet a lot. I take them out of my pockets and put them on a flat surface when I get home which means they are always in one of like 4 different places tops, but in two of them the vast majority of the time (dining table or desk).
Surely there are natural places those things end up?
We have a similar technique, I put my stuff in the same place all the time. But only because I was sick of misplacing them for many years.
I think there are a lot of people that don't have tendencies towards systems/self rules to solve issues like this, so they casually smash through life care free and forget where they put their keys "this time". (based on many people I know)
It isn't a system I developed to remember though, it is just... I put them somewhere sensible where they won't fall behind something or scratch anything etc.
My keys are often in different places, it is just that the list of "sensible" places isn't very large so if I have forgotten checking them all takes practically no time
EDIT: I should say not a system I developed consciously, I do have ADD so my habit of putting things in sensible places generally might be an adaption to that, though if so it happened before I even had keys to lose
We may be mincing words, but when I say "system" I mean "I decided to try and only place my keys in reasonable places, always... and these 4 are the most reasonable."
Where other people may have made no considerations at all where they put stuff.
I feel like "System" is a bit of an extreme term. "Sensible" also means natural. Like, either they go on the kitchen counter, the dining table, or my desk, or occasionally the arms of the couch usually because those are the places that have space to put things like phone/keys/etc when I empty my pockets.
The only considerations are: Is the place convenient (read nearby when I'm likely to be putting things down)? Are they a flat and stable surface?
That's it. I feel like if people don't make those sorts of considerations surely they are just dropping shit on the floor
1. Care about the subject
2. Focus on memorizing it: This may seem dumb, but how many times have you forgot where you placed your keys? If all you do is momentarily state to yourself "I set my keys here" when you put them down, it's almost hard to forget.
3. Don't eat white sugar or white flour processed, or other foods that may cause you to loose concentration. (I tested this theory when trying to memorize stuff. Crazy the effect it has)
4. Associate a picture (with an action or something outlandish) with the item. You can take a list of 20 items where most people get only a max of around 4 items, I can memorize the entire thing by making a story with the items. No practice needed, it works the first time for most people. Works for memorizing directions as well. (too long to explain the entire process in a comment)
These are just shortcuts though... (from a few memory courses I took in the past)