My big leap forwards was buying the QuAx Luxus 20. It replaced the unbranded 20 I started with, which had way too short a seat post and a way too small a saddle. (The QuAx also had a better tyre but I literally wore that down to the canvas in two weeks.)
Suddenly I went from doing tens of metres, to hundreds of meters, then to kilometres within a month. Like the rainy night riding finally clicked for me in my front yard, every time I made an advance it spurred my enthusiasm so I tended to ride even more and make big leaps quite quickly.
I took to sitting down quite easily because I was learning under the instruction to sit up very straight with weight on the seat. I now know that those instructions also made it harder for me to get riding but it meant I had good technique when I did finally get going.
It is important to realise that learning to ride a unicycle is a journey rather than a goal. It doesn’t matter how long you take to learn or what you learn first. (Some people start by leaning to mount into a still stand.) Every kind of learning experience helps build a part of the incredibly complex neural network the rider builds in their brain.
It was the same when I learnt entirely on grass until I could ride ten metres. Sure made it hard to learn but when I went out the front gate I was well prepared for the irregularities of old concrete paths because I understood weight distribution between feet and backside.
But if you find yourself riding around standing, just enjoy the workout. It will make you a stronger rider very quickly. That strength provides the power required to easily adjust very rapidly, which in turn improves the balance performance. You can more easily accelerate out of trouble. Better balance makes it easier to sit down. Problem solved.
There is no bad way to learn if you get there. Fortunately most riders gravitate (quite literally) into sitting because their legs demand it. Unicycles are so unstable that riders either develop good technique or eventually give up.
The central solution to riding well is to just keep riding. You will achieve unexpected levels of skill that you had not initially imagined, a lot sooner than you ever expected. That stage of learning is really fun.