Watch the Karen online guitar lesson by Adrian Legg from Fingerstyle Revisionist: Adagio Songbook
The tuning for this piece is EGDGBE, which is standard except for the fifth string going down. This gives us our 1-6-4-5 sequence. There are a few problem areas here, the first being a bend going into Bar 3. Push the bend in hard enough that the strings sink into the skin, actually going under the string. Grip the guitar neck firmly to make the bend easier.