4 x 4 Warm-up [SWU]
The goal behind this exercise it to build dexterity in all four of your fretting fingers. And also to build coordination between both hands.
This warm up actually has 4 different levels to try. As you go up in levels the warm up gets more difficult. If you find one too easy just move onto the next.
Before focusing on building speed, focus on being able to play the exercises cleanly at a comfortable tempo. Speed comes with good playing habits!