IMO minimalism is an amazing tool for people with shit attentiveness, that removes many distractions and places where things can get lost into. And this might just be me, but i find that it has helped me flip the spending habits 180°, so i'm if anything too reticent to spend money.

Some other things that help me is using the P!n app on android (it's available on f-droid, no clue about gplay store) to keep a persistent notification at the top of the list, so important to-do items are constantly shoved right into my face.
I make ample use of the calendar app with default reminders set to 1hr/30m/10m before the event so i have plenty of time to prepare myself and yet won't forget about it.