I don't really plan well. I'm just extremely autistic when it comes to organizing so that I always know exactly where I put something once it's been organized.
That said, there IS one way to absolutely make sure that I always do something.
Make a promise.
It's something that I would absolutely recommend that everyone learns how to do. Basically, if you say the words "I promise" to someone, you absolutely HAVE to do that thing whenever you said you would.
Promises cannot be broken unless they become physically impossible or would conflict with other core values.
Promises cannot be made with yourself.
Promises are valuable, don't throw them around as if they were nothing. I will sometimes go months without making a single promise. But you better believe if I promise something, it WILL be done.
The words "I promise" might not work for everyone, but my advice is still the same. Insert a core value within yourself that you absolutely despise not being able to fulfill. Use that to your advantage when you need to complete important tasks.
The most important step to getting shit done is to take the first step. Inserting that little push from your core values or morals is enough to get your started. Once you're started just use will power to push through it.
Eventually doing things will suck less and you won't have to resort to "tricks" to get your shit done. Hope that helps, anon.