One way to improve your guitar technique besides practicing your instrument is strengthening the muscles in your hands and wrists. Unless you already possess fingers like carriage bolts and wrists like tree limbs, your playing will benefit from increased hand and forearm strength. I would like to pass on something that has made a difference for me.
While gift shopping last holiday season, I found in a Sports/Specialty store a product called Power Putty (Sports Health Products, 527 West Windsor Road, Glendale, CA 91204). What you get for your six-to-ten dollars is a racquetball-sized gob of what I knew as "Silly Putty," a silicon rubber compound that stretches, bounces, and lifts ink off newsprint. Power Putty is blue and comes in a little plastic fist. The harder you squeeze it, the more it resists. Used for years in the rehabilitation of hand injuries, this stuff is aimed at professional and amateur athletes, sportsmen and musicians (that's us). Included is a booklet of exercises for strengthening the hand, fingers, thumb, wrist and forearm.
After a few weeks of squeezing the putty a half hour or so a day while reading or watching TV, my hands felt like I'd just come off a four month tour. Playing became more joyful than ever. When I picked up the guitar, I would reach for new runs *and get them*, and generally play with more authority and agility. Kneading the stuff is a great prep before shows, too. Your hands are warmed up before you play a note. Also, it's fun.
Power Putty comes in three grades of resistance. I have the medium and firm ones. Strongly recommended.
Now, here's a trick that's as old as the calluses on Les Paul's fret hand, but maybe it hasn't occurred to some of you.
If you need more sustain and feedback for legato passages or effects than is provided by any overdrive or distortion box you may be using, it helps to mechanically couple the guitar to the speaker cabinet. After setting your amp to a healthy volume, hold the headstock and/or body of the guitar against the speaker cabinet. (Experiment!) You should experience sustain and feedback for days, as you flog your whammy bar or just generally annoy your neighbor. Enjoy!