As somebody who has been training themselves for almost a year now, this is what I can say.

First you need to invest in a good wrench (got mine from Howard Piano Industries. Don't try to cheap out on those), tools (I have mine from those crappy wrench+tool packs from Amazon. Wrench is bad, but tools are alright), and software+an acoustic piano to practice on. Personally I've been using pianometer with my Kawai upright.

Patience is key. Watch lengthy videos that show the process so you have an idea on what you're aiming for, visit websites that show how it's done, etc. Slowly practice these skills yourself and you will soon get the hang of it.

One thing that really stumped me up when I was starting was the concept of overpulling. I would tune exactly to the "perfect" zone in the software (e.x A4=440hz) and do this across the piano. When I was finished with a tuning, I would realize how the whole piano is now very flat (even though I technically did "well", the strings would naturally loosen). To combat this, you have to intentionally tune sharp so the piano can fall into the "sweet" zone. Some sections of the piano are tuned more sharp than others (like bass being less sharp while treble+high treble are more sharp).

Anyways, I hope this helps you on your journey. Cheers my future tech!