Once you do this long enough, you can write a book or two about getting started... Here are my personal favorites:

• Cannabis is a weed. It will grow everywhere, if you let it. (Most important part. New growers often overdo it, slowly killing their plant with love. Just let it do it's thing and wait)
• Make sure you understand the basics about substrate, light, heat and cycles of growth. Get a cheap LED growlight. Don't bother with soil/coco, start with hydroponics (it's very easy for beginners).
• Don't invest too much money in your first grow. It will come over time.

And, of course, make sure you don't do anything illegal...or do it, I'm not your father.