One thing that I do is jotting down stuff. I think it was the writer James Salter who said you should write down the interesting things you hear people say. Along that line, Ben Franklin said that faded ink is better than the best memory. I write stuff down I hear, along with stuff I read that’s interesting. I have to do it soon before it fades into that marshy holding area for memories that’ll soon be forgotten.
For example, years ago on a camping and surfing trip our campground neighbor told me a story. Not a great story, but in the course of telling it to me, he described himself as a rogue individualist. In his daily life he was a plumber, so his image of himself in the story really stood out; and I wrote it down to help me remember the oddness of that moment.
If you try jotting down interesting things you hear you’ll have a good memory no matter what you decide to do with it.