You may refer to this page for links and suggestions for helping your child with neatness in handwriting.
In the classroom I encourage a 'tripod' grip. The thumb, index, and middle finger should form a triangle of support around the pencil, with the top of the pencil resting on the hand where the index finger meets the thumb. I remind students that the "last 2 fingers should tuck in for a ride."
I found this page to have some fun and useful activities to help with handwriting. I especially like the "Rainbow Letter Formation" and "Pencil Control Excercises."