At 30k miles, coolant should still be good, as Toyota now uses long life coolant,think Toyo claims 100k miles. Should be no need to clean battery terminals, unless there is corrosion on them, may want to coat them with protective coating like vaseline. Look at service interval manual that came with your Sienna for maintenance items. At 30k, likely need engine air filter and air cabin filter change, along with oil change. May want to change tranny oil, check it to see whether it's still nice and clear red.