There isn't a skin that magically makes you better. Its personal preference, try different skins until you find one that works well. Here's a dropbox with a few different skins. I personally use an older version of the o2jam square note skin.
Looking for mods for my mania map Minori Chihara - Kyoukai no Kanata (TV Size). Need some tips on how to improve in osu!mania? Try reading our guide and map suggestions! Need some tips on how to map in osu!mania better? Try reading this guide! Looking for the o2jam skin I use? This folder has it and a few other o!m skins! Message me if this link doesn't work, and I will update it.