I try to put as much is needed not on the heavy side. I wipe it as soon as i put it on. but i know some people can wipe it off the chrome after it dries.
you can search for tips in the hints and tips section.
I hope that helps.
There is many way of doing the black wash. The way I do it i use flat black paint apply to the grill then with a rag or paper towl wipe off the extra paint. so all the low area will have the black paint.