When I first got back into the hobby a few years ago, I had an 8" SCT, Celest Nexstar 8i, a basic scope by today's standards but all the same a very nice set of optics and slow, f 10, so looking for advise I took a road trip up to the only brick & mortar store of telescopes in the area.
Man what a great staff, very helpful and didn't try to empty my wallet they answered my questions, so I started out with ES 82's, 8.8, 11, & 14.
They were fantastic as far as I was concerned, then came this site, and a 10" f 4.7 Dob, hooked past the barb.
The edge of the view wasn't as sharp, so I got an HRCC, learned how to use it, then came the 100's, when you got real estate, use it, right.
Lunt/APM's, then ES, now Ethos, but the first few views using the HRCC and ethos weren't what I had hoped for.
Now I have a Paracor II, the views are what I was expecting, so in designing eyepieces and other light control lenses I've learned it's best to stick to one brand, Al designed both to work together.
Now I've experimented with a few Short Fast refractors and discovered Naglers work better in them than ES do, better edge correction for fast scopes.
I've also had a few different brands of eyepieces that were less expensive, more affordable to most beginners,
I've learned that long eye relief unless the eyepiece has a nice twist up cup are not very good starter eyepiece's,
It takes knowing that there are black out area's so the twist up eye cup can be set for proper distance.
So now to the filters, I've learned, and studied, read & read & read, topics, reviews and yes, your eye will see something a bit different than mine same filter same scope.
Also there's a huge difference in quality control of mass produced less expensive filters,
Most older, retired eyeballs have cataracts, fact of getting old, things break down, the more floaters you see when viewing the greater the odd's that you have a cataract starting, cataracts disperse detail, the brighter the target the greater the glare and wash out, the less a filter will do you much good.
99% of the time I recommend the OP's of the beginners forum to watch youtube video's and reviews before purchasing anything, keep reading and asking questions before you buy anything.
Now owning 3 Short tubes, a ST 90, ST 70 and a WO Petzval 66, the SCT & Dob and full circle back to a Mak.
When in doubt, buy a Nagler
I've owned more than thirty different filters, I use 5.
So what was the question again?
Right, not a question but a what have you learned, I've learned I could be driving a Porsche if I'd hadn't got back into this hobby.