There are basically three types of lines: straight, curved and squiggly.
Lines can be made very interesting by Varying the thickness, color, direction and number.
How many kinds of lines on this page do you see?
First, straight we all know.
Second, curved, we all know.
Broken or interrupted lines add interest
Jagged or scribbled are interesting.
Thick and thin lines are very interesting.
Adding and combining groups of lines will create textures.