*Play each string one by one like first play high e than b than g d a E and go reverse like E a d g b e
By this you can able to increase you speed on strings and you can play them easily when you get the good speed you can proceed to next lesson.
*Play alternate strings one by one like High e than g , b than d , g than a , d than E ((1,3),(2,4),(3,5),(4,6)) and reverse of this ((6,4),(5,3)(4,2)(3,1))….
By this you can able to play riffing easily
(Do not forgot to watch the video for better understanding)