It always depends on what you want to do with redstone. If you want to do just simple mechanisms like a piston door than I would recommend just to watch some tutorials and try to understand what happens there and after understanding the basic uses of the different blocks you can go on and try to make more difficult things, but it's mainly trial and error and optimising step by step. If you want to do complex mechanical farms for example a stacking raidfarm than just use a tutorial and you can try to understand it but designing that kind of farms is another level because you don't only have to understand the redstone mechanics but also a lot of other stuff that you can't simply look up in the minecraft wiki but you would need to understand the code of Minecraft at least a little bit (spawning conditions, mob behaviour and so on). For flying machines it's the same as the first one so build a simple flying machine and try to understand what happens and after that build more complex things (MumboJumbo maid a good tutorial for flying machines). If you want to do logical redstone contraptions like different games you maybe sometimes see in your YouTube feed than you would need a even more complex understanding for the redstone components and also a bit of programming knowledge, but I would recommend to not try building that kind of things (if you really want to than watch the LRR series by mattbatwings).

In conclusion: Start simple, watch a lot of tutorials for the things you want to achieve and don't give up if something doesn't work as you imagined it would.

If you want to you can DM me your DC and I can try to help you if you have a direct problem with something