Our hands were designed to simply grasp and let go - not for lightning fast licks that run down the neck. Like all other exercises, you first must warm up to prevent injury. Warming up slowly increases your body temperature, which increases the flexibility of muscles, ligaments, tendons and cartilage - which leads to fewer strains, sprains and tears. It also increases blood flow, which will help you play harder and faster.
When you first begin to practice, try to follow a routine. My routines vary each day but daily consist of warm-ups, many fret stretches, and taxing guitar chords. Depending on your preferred genre of music, a simple cover of a song or at least part of a song may suffice. As I grew more skilled, I tended to lean toward more physically demanding pieces - but everyone is different.
Here is a good guitar exercise to build speed and dexterity.
e|--8-7---------6-5---------------------------------|
B|------6-5-8-7-----8-7---------6-5-----------------|
G|----------------------6-5-8-7-----8-7---------6-5-|
D|--------------------------------------6-5-8-7-----|
A|--------------------------------------------------|
E|--------------------------------------------------|
e|--------------------------------------------------|
B|--------------------------------------------------|
G|--------------------------------------------------|
D|-8-7---------6-5----------------------------------|
A|-----6-5-8-7-----8-7---------6-5------------------|
E|---------------------6-5-8-7----------------------|You could even play this backwards if you like, but I'll let you practice your tablature reading skills for that. :)
15 minutes a day is all it takes to see great improvement.
