Tangentially, this reminds me of my own personal cure for when "gear acquisition syndrome" flares up; I just remind myself: put Yo-Yo Ma behind a $40 cello made out of balsa wood -- you will get music. I haven't touched a cello since high school, but put me behind the priceless Stradivarius Ma once accidentally left in a taxi -- on a good day you'll get Penderecki, on a typical day you'll get the sound of kittens being tortured.
A thousand times yes (and applies to all aspects of composition, not "just" orchestration). This is one of those fundamentals to return to/constantly remind oneself of no matter how long you've been at it. Even bonafide virtuosi like Ravel quite often adhere to exactly this -- and even when they're choosing to push the envelope, they always do it idiomatically, so the performer responds with "cool, thanks for handing me some fun challenges to bite into" rather than "wow, you're a real jerk ..."
Definitely lot of good advice in this thread - but personally find it quite tailored to folks that are looking to do this professionally or work with professional orchestras. For others of us who do this more of a hobby / have limited time and want to keep it "fun" / do not quite aspire to replace the day job - and find themselves "stuck" with a piano sketch or something, I can offer a different suggestion - Evenant's "Cinematic Music: From Idea to Finished Recording".
I grew up playing the piano (along with a handful of other things), but wouldn't consider myself proficient at writing on staff paper (quite poor actually) and my sight reading is ok, if I have lots of time to work everything out. I've bought a lot of material over the years - from Visual Orchestration, to Scoreclub, to Mike Verta's courses, to ThinkSpace, to private lessons for a few months. I was even around on the Garritan forums back in the day when they first launched their Rimsky-Korsakov orchestration guide. All of these felt a bit advanced or not quite getting to what I needed. It was like getting dropped in a foreign country where you don't know the language. Or going from 0mph to 25mph - if you're standing still, 25mph is quite fast! They also felt rather academic at times (some more than others) - and the last thing you want to do after coming home from work is calculus homework when you're still trying to understand algebra!
Then I found the Evenant course and what I like about it is 1) the music is more modern, which does make it more appealing to go through than studying something like a classical piece from a hundred years ago (personal opinion) 2) you are actually watching somebody orchestrate a piano sketch in real-time, and 3) it is the 0mph to 10mph step I was missing. It doesn't go as deep into orchestration as these other resources, but that wasn't what I needed. I needed to see the building blocks of melody, harmony, rhythm, texture, etc. and how those map to instruments / instrument combos. They touch briefly on things like chord voicing, but generally, not a strong focus. I did some of the Bach chorale harmony voicing with Thinkspace, but I didn't really get to apply any of it - it felt very academic and time consuming (and yes, I know that is important, but when you have limited time for a hobby, the last thing you probably want to do is spend an hour on a handful of measures working out if you have parallel fifths)! I view that stuff as refinement on top of more fundamental concepts. Without the fundamental concepts, what are you actually refining?
Christian Henson from Spitfire talks about this too - he doesn't come from a music theory background and he never talks about things like voice leading, contrary motion, etc. in his videos. He's learned those over time of course, but fundamentally, he starts with the core of the music and what sounds good to him. That was what I was missing with these other resources. Now, I feel more confident in tackling those other resources because at least the music has gotten off the ground - which to me is 80% of the battle. You can always go back and refine it to achieve the other 20% using more advanced knowledge.
Anyway, those are my 2 cents from the non-professional / hobbyist perspective!
Edit: Whoever recommend this - great recommendation! My kind of video.