If there's one thing in common for beginning guitar players, it's the sore fingers. To play guitar, your hand muscles must learn stretch and hold new positions. To toughen up and strengthen your fingers, you'll need to limit your practice time and incorporate several hand exercises. With dedicated repetition over several weeks, your fingers should be tough enough for guitar playing.
Play every day for 15 to 20 minutes but no more. This will work your fingers but the limited time should help prevent calluses or cracks in your finger tips.
To speed up toughening your fingers, get an emery board and gently scrub your finger tips for a few minutes, such as while watching TV. If you don't have a emery board, try using fine grit sand paper.
Get a hand tool, such as a Gripmaster, and do 10 to 20 repetitions on each hand each day after step one.
Learn a few barre chords on the fifth and sixth strings. Guitarist Steve Krenz says to do 10-minute power workouts that transition between several barre chords on one string (see Resources).