For me it was "buy high quality pillow" because you sleep for one thrid of a day etc. I needed a new pillow anyway so I came to the store and bought the best they had. And it was ... ok. Like it's a fine pillow but my sleeping haven't improved really, it's basically the same. So I was disapointed :(
Writing notes for myself to remind me to do something. The problem is that I don't remember to look at the notes. What's happening is that people are telling me advice that worked for them. That's very nice of them to try, but when I've tried similar systems for decades and they always fail, it's time to try something new.
I use calendar events and put reminders depending on how important the task is. Like if it's my mum's birthday I put a reminder two weeks before (so I get her a gift) the day before and then the same day in the morning but if it's something like remembering to call a company or something I just put one reminder at 3 pm on the day of the event.
You can then snooze the event for as long as you want until you have time to take care of it (at least on Samsung's Android)
This, it's not enough to just create a note, the note has to jump out and harass you. Then, you also have to religiously act on or get rid of your notifications. (I hate notifications a lot, so I tend to have few apart from things I'm notifying myself about. I hate those too.)
I have a phone with me all the time and I have to be in a specific place to see notes, so notes don't work for me. I do have a button on my phone I can talk to and say "Set a reminder to feed the animals at 6:30" or "set a weekly reminder to take out trash at 10pm every Friday" or "text her back in an hour" and then I get an alarm I can't really ignore, I have to do something with it.
I tried this. Same problem. If I need to remember to do something I put it in google calendar as a task I need to check off at a specific time. Highly effective... for me anyway.
I sometimes use sticky notes in the bathroom. I stick one on the mirror right where my face appears. That way I will at least read it before removing it.
But once you get used to it you will stop paying attention. Now I only use it occassionally.