Every dragon needs a mother.

Intelligent selection of spells is a must. Using their huge flight movement with flyby attack (yes, usually with their breath weapon). Use Scintillating Scales if your mages get happy with touch attacks. Deathward, Mindblank, True Seeing. Metabreath feats can be pretty nasty.

More than anything else, give it a personality. Dragons are long-lived, intelligent, creatures. Not mindless beasts. Give them a plan, a reason for attacking.