Watch the Drop D Tuning Part 2 online guitar lesson by Richard Gilewitz from Fingerscapes
Take notice in the first two measure of the importance of the right hand position and the need to extend the thumb to the left of the fingers. You should be able to easily see how it is desirable not to allow the right thumb and index finger to 'crash' into each other OR for the thumb to tuck inside the right palm. Be sure to maintain a slight bend in the right wrist when obtaining this angle of attack. During measures 5 to 6 you should notice the importance of the left hand index finger and how it slides from frets 2 to 7 and then back to 2. This is the main theme of this portion of the tune and the gliding effect should be given great attention. Keep the slide relaxed and in time. A metronome will do wonders for you.