Main thing is the get the crap off it before you actually lay a finger on it. I'd use a pressure washer and be patient, at least that way you should be able to dislodge the crap before you put a cloth on the car and swirl it all over the paintwork.
2 x bucket method with some decent lather will be a must after that as there will still be plenty crap on the motor and you want to be putting a clean cloth on there as often as possible. Ive found this made a big difference to my own cleaning regime.
Main probs I found doing this at the weekend was I couldnt dry the car quick enough before it started freezing over again and I was left with an ice rink on the drive which caused a couple of issues.
I think there are one or two detailers on here who will be along to offer more advice, but I think thats the basics from my point of view.
If youve got the time you could look at paint sealant and the same for alloys as they'll get a hammerimg from the salt and general grime. North East Detailing stock a good range of products and are always good for a bit of expert advice.