Watch the Harp Guitar Tips online guitar lesson by Stephen Bennett from Harp Guitar Repertoire
Here they are in a nice concise list:
1) Settle on a tuning and get comfortable there BEFORE you go wandering all over the place.
2) Mute often – just get in the habit of doing it – don't make me come over there.
3) Think Minimally – choose your notes wisely and you don't have to have a thousand of them. I'm specifically talking here about the sub-bass strings, but this is a good principle for music in general, at least to my way of thinking.