Heighten your daughter's interest by pointing out some of the exciting things about camp--activities, special events, new friends...
Introduce your child to others in your community who will be attending camp.
Familiarize yourself and your daughter with the camp environment and daily routine.
While painting a bright, promising picture of camp, do not forget to mention some of the not-so-glamorous realities of rustic outdoor living; there will be bugs in the showerhouse and frogs making noise at night, and these incidents should not come as a surprise to the first-time camper.
Prepare the child to care for herself--have her spend a weekend with a friend or a relative, help with the packing, learn to make her bed, set the table.
Speak openly of homesickness before camp--once your daughter understands that homesickness is natural, she may accept it with less anxiety.