Alright, some major essentials:

- Know the difference between sativa and indica.

- Know what hydro, brick, mids, and sinsemilla bud are, and how they're produced, and the highest prices you should reasonably have to pay for them in your area.

- Know at least how to properly load one form of smoking implement: How to pack a bowl/bong really well or how to roll a good joint/blunt. Over time you should, preferably, learn how to do all of them.

- How to properly conduct a deal. Go with friends, and learn how.

- Know the cannabis culture's terminology and slang.

And most importantly:

- Know the positive, neutral, and negative effects of cannabis. Use it in a way that is enjoyable and doesn't intrude in anything, and don't let it become a major problem or overdo it.