Here are a few resources to get you started.
If you haven't already, get my Calligraphy Beginner's Kit. It has everything to get you started: Sumi Ink, Nikko G nib, penholder and a pad of smooth paper.
I cannot rave enough about this calligraphy classes by Bryn Chernoff (from paperfinger.com). This is where I discovered (and got hooked on) calligraphy. Skillshare is a paid site ($8USD/month), but this link gets you 1 free month.
Nothing like some good advice on proper penmanship from 1888. Click here to browse through the PDF for free.
Even though traditional calligraphy has at its core a rigid set of rules, it doesn't mean you cannot play and explore in a more fluid way. Modern calligraphy (also known as gestural calligraphy) allows you to follow the natural movement of your hand and follow your own rhythm. Have fun!