Clean with favorite spray-on wheel cleaner, rinse off, soapy old rag and water, rinse.
Polishing:
Any polish will work - I've used NuFinish and Metal Gloss with good results- although I hear the Mothers and Turtle Wax polish work great.
Sealing:
Metal Gloss sealer - made my chrome wheels feel waxed when cleaned and it lasts. Don't know how it works but this stuff is great - sorta pricey though. Picked it up at the L.A. Auto Show in the aftermarket section with a nice discount.
http://www.metalgloss.com/