Hi, I'm 62 years old and have been playing for about 8 months. What is the best way to increase the speed on chord progressions. For example I can play a progression at 70 bpm using just down strokes but when I play down up it slows me way down. Should I aim for more bpm using just down strokes or should I go slower and learn down up instead.

Also, say I'm at 40 bpm how should I increase the speed. Should I go up to 42, 44, 46 and so on or should I do as my buddy suggested. He said if I'm at 40 to jump to 60 for 2 minutes then back off to 45. I'm not sure how to progress