Don't worry about rust, most steel frames will outlast you....I don't really do any special cleaning. Spraying a bike with a water hose or washing it in a shower is a bad idea because water and moisture will get inside a frame and stay there for a long time...Serious rust usually starts inside the frame and not on the outside...I usually just wipe the dirt and salt with a dry rag. The only thing I rinse regularly with water is disc brake calipers to get all the salt out of them...I recommend spraying some rustproofing oil inside a steel frame and don't worry too much about the outside. I have two steel framed bikes which are 12 years old and have been ridden in the worst winter conditions and the frames are as good as new. Both of my frames have been treated with rustproofing oil on the inside.