Visualisation using a memory palace or journey method.
You choose a place or route that you know very well. You then put the things you need to remember at places along that route with things to remind you of said item. This can be done in a palace/room or a journey.
For instance if you wanted to remember a shopping list in a palace you would:
Think of a room associated with those items - the kitchen, then you visualise going into the kitchen on the counter to the left of you is a huge marrow with a sheep nibbling on it, the creature jumps down and runs to the sink where it washes up the dishes, finally putting out the rubbish. This reminds you to get a marrow and a joint of lamb for dinner, washing up liquid and bin bags.
You would only have one item per place in the room, make it as huge and memorable as possible. There are lots of videos on You Tube telling you in more detail, but that is the basics. Keep running over the journey in your mind to build pathways in the brain.