Crypto trading does not require any special skill beyond usual trading, which means you may not need anything special just because you are getting into crypto trading. But, you must need to have all the basics of trading a market which is more important. For that you need to practice on any demo account which is provided by Forex brokers or crypto exchanges.
You started with leverage trading? That must be one of beginner's mistake. Spot market is comparatively less riskier hence that might be a good starting point for every beginner.
I would say it requires a great deal of mathematics. I mean if you are having trouble as much as addition and traction, then you would not be able to trade very well. Which means that you need at the very least a basic understanding of math. I would agree that leverage trading as a newbie is the biggest mistake anyone could make, I have been in this market for years and I still avoid making leverage trades.
The simplest one is long term investment, but if you really want to start somewhere, then spot trading is a lot better. I do spot trading here and there, not a lot but I do it just in case there are things that I see and do not want to miss out.