I like cobalt blue, white, and forest green for wrought, cast, and bar-stock iron furniture. and personally, I prefer the satin finish to the high-gloss.

depending on the health of the iron (if the rust is built up to the point of bubbling and flaking, for instance) Rustoleum's made a career of 'no fuss' metal painting, and their paints are self-priming to a degree.

that being said - spray paint is far easier to apply, but you'll need to recoat it four or five times to get something even close to as solid a coat as you'll get with one brushed-on layer. if the furniture is relatively simple, I'd go with their enamels in cans, and a disposable brush.

I had a friend who recycled his old dining tables and furniture as patio furniture and I have to say that it worked out for him rather well as it added a rustic look to his garden.

I have old wrought iron furniture. It is hard to change the color without some serious work. You need to sand well and be sure to get rid of any rust or at least use a rust inhibiting primer after sanding. I have always gone from one dark color to another (brown, green, black). I don't know about going from black to white. I have heard people say they have taken pieces to places to have them powder coated and one person suggested a car painting company as an option if you can get them to do it for you. I have considered asking the body shop guys who have fixed our cars when they needed body work. haven't yet because they are always so busy.

Just saw the date of the OP. Sorry-didn't realize someone had revived the thread! :)