I'll tell a story that sounds like the message is "buy fancy gear," but in fact I wholeheartedly agree with everyone here who says take lessons: in my limited experience, good form and practice are what build confidence. But also: definitely demo if you get a chance, if for no other reason than to get a sense of how different skis feel, what that means for you, and which skis make you feel confident, which ones expose your weak areas, etc. All of that will help with your skiing overall.
So here's the story: I took a couple of lessons and worked hard on my form this season (my first in 30 years) on a pair of K2 Comanches, which I think came from some dusty, neglected back closet in the rental area. Or possibly a time machine. They were basically fine: a limp-noodle beginner ski with dull edges; probably hadn't been tuned in a decade. But I learned the basics and developed some good habits and was having fun practicing as much as I could.
The first fancy/ spendy thing I bought were good boots from a quality ski shop that takes care with fitting them properly. Nothing hard core: just some beginner-level Salomons. I figured that would help me progress better than staying in the rental boots, and that I didn't care too much about what type of ski I was on as long as the length seemed right.
Then one day for fun I paid $50 bucks and demoed some skis at Camelback (in the Poconos). First ski: Rossignol Temptation 88. Hated it. Probably I just didn't know what to do with it. Brought it back and the guy recommended the Volkl Charisma, so I took them out. On the chair ride I looked them up on my phone and saw that they were billed as "expert" skis, and I thought "No way are these for me. It's probably not even safe that I'm on them. I should ski slowly back the the lodge and return them, backing respectfully away from the demo counter, averting my eyes from all of the other skis I'm not worthy of."
So I got off the chair and proceeded to style the green slope with unbelievably precise, powerful carves of varied sizes. (I know, it was just a beginner slope, but I hadn't come close to that feeling of precision before, or to that level of confidence and competence. Holy cow!) So I went on some blue trails and did the same, with a few predictable intermediate mistakes: backseat driving, picking up my downhill ski, etc. whenever anything got a little steep or choppy. But the bottom line was that these skis literally made me a better skier. They didn't let me get away with lazy form, and they were carving machines with amazing edge hold, which meant I could control my speed better, make turns with more intention, zip confidently around obstacles (i.e. snowboarders strewn about the trail as though they'd been casualties of an artillery barrage).
Here's the takeaway, I think: The Charismas made me a better skier because they allowed me to really use the skills that I had been honing on the wet noodles. They showed me why good form and technique mattered, and where it could take me. They would be terrible beginner skis, I'm sure. But I would have avoided them as an intermediate, too, because they were labelled "Mega-Expert-Shredder-Mountain Goddess" and that ain't me.
I'm so glad the guy in the demo cave prodded me to try them. I'm about to buy a pair to be my frontside carvers and main ski. I'm not ready for black diamonds yet but I'm getting there, and not just to hurl myself down them as a flailing, terrified victim of gravity, but as a confident skier with good technique enhanced by equipment that works to my advantage.
