There's no doubt that assisting is, hands down, the best way to really learn how to shoot professionally. Set etiquette is one thing that will come with time, but equally important are the little things that all add up and that will make you the best second pair of hands to have on set, second to none -- if you pay attention to these things. While everyone has their preferences, it's always a good idea to research different ways to do the same thing, and to then intelligently choose the best way you can find. DSLRVideoShooter's Caleb Pike took the time to share a few more general tips that are not just good suggestions, but that are absolutely essential to being a good assistant if you want to keep coming back.
Wrapping stingers correctly, tightening stands with the legs perfectly aligned, and wrapping with consideration for the next shoot's staging are all things that are industry standard. You should know how to plug an extension cord in safely (I have my own way that 90% of the industry knows about, yet doesn't follow, but I will maintain that it's the best: picture the very first step of tying your shoes, and then "plug in" the tips of your laces -- that'll prevent an unplugged cord if someone trips over a cable), among other simple things. But nothing will teach you like experience.
Want the best set experience in which to learn? Find a student set. They may be a bunch of kids, but I'll tell you what: they still do everything the way you're supposed to do it, which in many cases is a great thing. You can't get lazy with your hours in this business, but some of the older guys and gals do get lazy with their technique when it comes to caring for grip equipment.
For Pike's full post, head over to DSLRVideoShooter.com (and go ahead and get lost in some of the other great stuff they have over there).
This is some invaluable advice! Thanks for the post!