What is the best way to refinish white wrought iron outdoor funiture?

wire brush the rusted areas, hose off the pieces (or use air hose to blow off particles left from using wire brush), let dry well the Rustoleum spray paint them any color you like. Works great & helps prevent rusting.

I agree with gypsydit, spray paint comes in a multitude of shades, paint lightly several layers.

then rinse. Maybe you could use some CLR in a bottle that shoots it thru your garden hose nozzle w/water. It's the same plastic bottle you would use for spraying weed/feed on your grass.Do it in your driveway or street so it doesnt harm anything.

Clean with simple green, then follow gypsydlt's advise.

As above, keeping in mind that darker colors get hotter than lighter colors but you'll probably need cushions or coverrs in the heat of summer

Use a wire brush, get all of the rust off and then use a spray paint for metal.