cleaning and keeping clean the engine

what is the best way to clean the engine. one thing i've noticed is lots of people have clear cars, but then they open that hood and awww, its horible. what is the best way to clean the headers, have a very small amount of rust starting to show up if u look real close, but i wanna keep it from getting any worse, and fix that little bit already there if i can. thanks for any input.