First off, Welcome to the Den. Injectors are nice razors to use. They shave a little differently. When I'm using my DE razor or injector on my work days, I usually only do one pass with canned foam (Barbasol) because it's quick. When I have more time, I will use a brush, nice shave cream or soap, etc. and take my time.
Thanks everyone! Makes sense, I will probably develop two methods depending on situation as well. Right now I'm just so eager to learn prober lathering and shaving that I do a few passes just for the practice!