Getting good speakers and headphones.
Once you get a handle on a good replication of what you're hearing, it makes a load of difference when trying to get the ideas into your daw.
I'll also suggest getting a computer that's optimized for audio work. Like the fastest CPU you can afford(intel, amd sucks;effecient hyper threading(i think)>MORE CORES LOL), 16gigs of ram for 64bit OS, and a decent graphics card (this will help with graphical processing and get rid of the burden on your CPU;nvidia)
I also suggest a desktop over a laptop. Mostly because if you're not a touring, it's just better to work with that due to it's power capabilities and expandability.
This probably doesn't touch on like "siqq wubs", but these things should be considered when your siqq wubs start stuttering and you have to deal with bad emotions that shouldn't be present. Just keeps you focused on your sound design.
Other than that, i just continued to do it. The youtube videos got me a basic understanding of the synths, but they didn't really teach me much because i already wanted to make things my own way.
I also read several books on the origins of synthesizers. I've also read more technical books about computer music, dry af and long but i got some bits out of it.
There's several reason, and several resources to draw on that encompasses "sound design".