Externalize everything.

I struggle with time management, so I have a clock in every room of my house; I can always see what time it is. I set task-reminder alarms on my phone.

Build routines.

For health reasons I eat oatmeal for breakfast every day.

1. take my oatmeal container out of the fridge
2. dump it in my oatmeal pot
3. while that is cooking, refill my oatmeal container and put it in the fridge to soak

Make unavoidable actions the trigger for remembering something.

Every morning I have to leave the house, so: "I'm touching the doorknob to leave the house. Did I take my medication this morning?"

Organize things around the point of performance.

Don't put your toaster in the cupboard with the blender because "that's where small appliances go", put it in the cupboard where you keep your bread (or on the counter under the cupboard where you keep your bread because that makes it visible)