Calligraphy PRACTICE, like playing a musical instrument, is necessary. It's the thing you can get lost in for long periods of time as the ink flows (or not) smoothly on the paper. I don't practice enough. It's something I'm working on rectifying.
Tools. So many choices. You have to try them out. Papers, writing medium, nibs. See what works for you. If something isn't working try changing any or all.
What to write? It's nice to have words set before you when it's time to practice. Poetry is a great choice. Song lyrics, your own thoughts.
A few of my favorites for ink are seen at the top. Higgins Eternal is a nice wet smooth flowing black. Walnut ink is earlthy, somewhat transparent depending on how thin you apply. MCaffery's Ivory is nice for a light on dark paper. Got mine from Wet Paint. No mixing necessary with those 3 so you can keep the momentum going.
This stuff is gorgeous! Fine Tec metallic water color. There are other color choices as well. An example of the far right color below.
Have a great week end!