Watch videos of great 6 string players like Steve Lawson, who I ended up studying with in the end when I was having problems adapting to the 6. When I first started on a 6 string about 15 years ago, I was still trying to play like a 5, particularly with my right-hand. A good right hand technique is to follow the strings down as you move, so if you're playing notes on the D string for instance, then you might be resting your thumb on the E string. Muting is very important, and slightly harder to do due to the extra strings.