A guide explaining the techniques I used to get good at the game real fast.
Guide to Improve Skills
Why You Get Better
Let's start with an explanation on what your brain does to make you better at a game. At first, you'll be playing conciously, deliberately moving your mouse/analog stick/trackpad to match notes. Then deliberately learning to tap the notes on beat. This is because you have no experience. Your subconsious mind hasn't had the playtime to create intuition. What I just said might sound very obvious, and it is. It's not anything you don't know. But it's important.
It might sound strange, but experienced players have to do very little concious work (other than paying attention, and maybe choosing where to look in the screen) in order to play even some harder maps. Sometimes I get sleepy as soon as I start playing. Sometimes you don't even have time to comprehend the movement you should perform based on the pattern you saw, but your hand does it anyway. This is because your mind has seen so many patterns, so many timings, and so many misses and successes by your concious play that it learned what to do in most situations without leaving anything for you to think about.
When you first get (or got) to color switches, you'll probably find them very hard. This is so unintuitive, there's no clear side I should choose to move in. So you had to choose. You could move in the same direction as the previous movement, you could move in the opposite direction to make up for space in the mousepad, you could alternate, you could do whatever. Let's say you chose the first method, which I imagine is the most common. OK, match in the right, I move to the right, match in the left, I move to the left. Now what? You keep playing. You're almost getting good at this. Then you get to the sax section on Believe in XD difficulty. ♥♥♥ this is literally impossible. There is no way the human brain has the processing power necessary to do these color switches. Please fire whoever charted this. Then 10-20 hours later you're doing color switches like they weren't even there.
How to Get Better: Challenge
Oh, here it comes. He's gonna say "practice" and be like "well it's different because I just explained some ♥♥♥ I saw on veritasium or something" and yeah. I am gonna say practice.
There are two ways to play this game. The easy way is to stick to what you know, find a song you like and play it till you PFC that ♥♥♥ and then find a new song to grind. The hard way is never PFCing anything. Leaving all those songs with a C+ rank in the basement while you try and tackle the ♥♥♥ sax section in Believe. Now, I'm not saying "don't be a completionist," because I'd love to do a TreXDer and PFC everything. I'm saying that's not the fastest way to get better.
Consider this: do you think you'd be a better mechanic if you fixed small issues in well kept cars or had to fix tons of insane tragedies in some poor mistreated 30 year old jeep?
When you play the same song over and over, you're learning very little. Muscle memory of a single song isn't intuition. Not only that, but it's also not time-efficient. If you already have an A rank in the song, there are few mistakes to be corrected. The more effort your concious mind has to put in, the more your subconcious mind will learn.
When I started playing custom charts (which I highly recommend) one of the first charts I downloaded was Paradisus-Paradoxum, by Stride and imfallin. Now, imagine me, a poor little addicted newbie with 40 hours and barely able to finish Expert songs trying an XD 48 level. As you can imagine, it went super well and I PFC'd it first try.
After 5 or so tries, I couldn't even get off the first few bars. Then I gave up, and downloaded some other songs. After a few more dozens of hours, I could finish XD 30+ levels without much trouble. Wow! Maybe I can finish that really hard chart if I put in enough effort, And I really wanted to finish it because I love the song. But nope, I could barely get halfway and that was the easiest half. So I had an idea so humongous-brain that even Newton would go crazy. What if I downloaded even harder songs? And it worked. With an amazing streak of less than C+ rank on every custom chart, I could beat XD 40+ levels. Take that Newton lmao. And then after downloading a few XD 70+ charts and getting my ass whooped by them and their color switches, I finished Paradisus-Paradoxum. If you go to imfallin's gameplay of it on YouTube you'll see my clearly (although briefly) documented journey in the comments.
So, what can you take from this? If your brain isn't begging you to stop and your hands aren't cramping, you're not going fast enough. And yes, I phrased it like that on purpose.
How to Get Better: Study
Okay, forget you hate the word "study" for a bit and hear me out. This probably isn't the most effective use of your time to improve your insane spinning skills but I need the content to make this guide seem more helpful. Anyway, if you're that desperate, here it is: learn the fundamentals of charting. Watch one of the RemiXD livestreams for the basics, and then just play good charts with that in mind. This exercise will allow you to practice making educated predictions on what a chart should have next, eventually letting your subconcious mind do the work once again and vastly improve your reaction times. Now, have in mind, this is only going to work with good charts. Anything from smb, Programmatic, Stride, imfallin, sodapants, HighCaliberTree, juch., Kali, Dama, Slival, Loosiano, Neppy, Zick and many others, study these guys.
Knowing not to expect backward spins or nonsensical alternations of beats and taps will give you less to think about, and in the long run, make you a better player. Also, this is going to be useful if you start charting yourself, which I recommend, it's more fun than it looks.
How to Get Better: Repeat (Sometimes)
Wait, this goes directly against what you just said! Ok, it kind of does, but hear me out. Some patterns are just too difficult to be doable after a few tries. For example, one of the patters I have the most trouble with are Zick spins, especially when they use matches or taps instead of holds, or change direction regularly. You have a pattern like this too, and those are worth practicing.
So if doing good in a level and suddenly this ancient monstrosity appears to kill you, practice it so you won't die to it again.