I'm working from this page of instructions, starting off by using the 2.0 mm felt-tipped pen.
First I set up guide lines. The x-height, that is the height of regular characters (x, e, c, i, n, u), should be marked in with 4.5 nib widths (4.5 x 2.0 mm = 9 mm). The ascender and descender heights should each be set in with 2.5 nib widths (2.5 x 2.0 mm = 5 mm). I also dropped in some perpendicular guide lines.
There are a few rules for creating Gothic characters:
- Hold the nib at a constant forty-five degree angle.
- Make all straight up lines constantly perpendicular.
- Relax, making easy strokes. (Prevents wobbly lines.)
After a bit of practice with the felt-tipped pen, I tried out the C-4 calligraphy tip with India ink. This tip is a bit narrower so could probably use narrower guide lines. I did most of the C-4 work (except the last "icicle" on the second line) without guidelines.
And here's another little try with only a base guide line: