Paper weight, tooth, and ruling

Hold a sheet and write one line. If the nib catches, the tooth is too dry for that pen. If the ink feathers, the sheet is too open.

For gel pens, a smooth 80 to 90 gsm page is enough. Fountain pens prefer something closer to 100 gsm, especially on both sides of the sheet.

Ruling is a preference, not a virtue. Dots keep sketches and lists in the same book. Lines keep longhand honest. Blank paper is for people who already know the margin.