Start up a dream journal. Get into the habit of picking up little details and describing them quickly but also on point. Then, after your dmt trip, try recording yourself speaking about the trip (i would say write it, but it's damn near impossible to focus enough to write). When you listen back to it you should be able to recall more and more tidbits of your trip. I know people who've gotten their trip recall up to about 45%, which is really good considering I usually retain about 5% x)