How do i make my plane go further?

I am making a balsa wood plane design rubber powered (squirrel design) and am wondering how to increase flight time it is in the air.How do i make my plane go further?Can you curve the trailing edge of the wings down a bit? This may increase the camber of the wing and give it some extra lift and keep it aloft a teeny bit longer. You might try it. If it causes too much drag, bend it back up a bit.How do i make my plane go further?Assuming this is a one design competition, make it as light as possibleHow do i make my plane go further?Increase the wing area will give if extra glide ratio