Welcome to the osu! forums!
. From my experience, I would recommend starting out with your mouse until you are comfortable with moving it, also you can use the keyboard and a tablet if you haven't already figured that out. Of course, this is all preference. I prefer to use a mouse and a keyboard.
For maps, I'd say stick to ones you enjoy and start out with easier difficulties until you are confident to move to the harder ones. Remember that this game is all fun, so please keep that in mind while you play.
See you in-game!