Here are two that I use regularly:
1)
In order to stay focused, every day I put:
[X] No internet
At the top of my to-do list. I pre-check the box, that way if I end up wasting even a minute of time on the internet (unless it's during a break time, like now) I have to actively remove that check from the box. Something about the immediate feeling of failure from removing the check keeps me from doing it.
2)
When I need to remember to take care of something, I take a trick inspired by ideas like the memory palace. As an example, if I need to remember to do something before I leave the house, I visualize approaching the door to leave, and imagine myself in a semi-panic state and think "I almost forgot to <insert thing to remember here>!"
Without fail, when I go to leave the house (or another choke point event) I remember what I needed to do. It's almost like putting a mental sticky note on the door.
2) When I need to remember to take care of something, I take a trick inspired by ideas like the memory palace. As an example, if I need to remember to do something before I leave the house, I visualize approaching the door to leave, and imagine myself in a semi-panic state and think "I almost forgot to <insert thing to remember here>!" Without fail, when I go to leave the house (or another choke point event) I remember what I needed to do. It's almost like putting a mental sticky note on the door.