Do some simple and basic stretching exercises for your fingers. Start with two clenched fists. Slowly unravel the fist, by letting each finger go in unison. For example, release the pinkies followed by the ring, middle index and thumb. Do this simultaneously with the other hand. Next, place the fingers fully stretched against the wall. Push your palm against the wall and then away from the wall 2 to 3 inches. Repeat again and again.
The best way to warm up the guitar and your preparation to play is by playing individual notes. Begin with notes that are played with your pinkie. Next use your ring, middle and index finger. Remember that you should keep the thumb on the lower back of the guitar neck at all times.
Now place all four fingers on the fret board. Start with the index on the third fret on the E string. Place your middle on the next fret down (the fourth fret). Place the ring and pinkie on the fifth and sixth frets. Now remove the middle, ring and pinkie slightly off the string. Play the E string at the third fret with the index. Quickly shift from that note to the middle finger on the E string. Play the note and quickly shift to the ring on the E string. Keep this same pattern, dropping down one string after the final note is played with the pinkie on each string.