Most important one (and everyone will say it again and again): Play more and practice.
You'll definitely get better when you get more hours in the game.
Try fixed scroll speed and not BPM scale (you can find it under the options).
Keyboards don't really matter, it's your own preference really. If you like playing on a mechanical keyboard, use that, otherwise any keyboard that works is fine.
For skins, you just need to try different ones and see what works. Try this one for example:
t/247348You can also find some skins with arrows or circles.
And lastly try to get more finger independence, learn patterns and play maps that you feel are difficult, but not impossible.
Don't forget to have fun btw, there is no reason to get better without having fun :p.