learning an instrument

[Charles McGuffin]

I still catch myself holding my pic wrong or only down-strumming sometimes.

Did you see was Jame Hetfield/Dave Mustaine do with only down-strumming? I actually got much better at strumming both ways, because at first I only down-strummed (or whatever it's called in english).

 

[Shadowstar38]

Cant help you with piano. But my best advice for guitar is Rocksmith. I was skeptical when I first heard about it but it works like a dream. After awhile you can play pretty much anything.

Though you have to already have the guitar to go with the game, so prepare to already be heavily invested in learning that particular intrument.