Making lists is my thing, I use the Microsoft To-Do app and make lists of what I need to get done for every day weeks in advance so I can stay on track and be productive. Sleeping well also helps me a lot, if I don't sleep good or if I barely sleep/ don't sleep at all I end up not feeling like doing anything and have a very difficult time focusing, so the day ends up being wasted and nothing gets done.
Getting rid of distractions is a big one for me too, I can't focus on things I need to if I have my laptop open or am on my phone browsing the internet. I get sucked in and hours go by without me realizing it. I do meditate sometimes too, and having a cup of coffee or tea or something like that also helps me focus