How to draw straight lines

To draw straight lines on the iPad in apps that don’t have a ruler tool, I use whatever straight edge I have laying around: plastic ruler, book cover, piece of cardboard, notepad, etc.
In the Paper app specifically I have journal page templates of “frames” that I duplicate1 anytime I need them. Saves me the step of having to redraw the same straight lines over and over again.
To copy a page pinch the screen to zoom out and then press and hold on the circle plus button until a duplicate button appears. Then tap that. ↩︎
Related

Switching tools with Paper
How to switch tools in the app Paper for iPad and iPhone.
How to paint smoothly with the brush tool
A smooth gradient can be achieved layering washes of watercolor on top of each other. Speed and pressure play an important role in how clean of a tone you end up with.

Mastering Pencil by FiftyThree
Learn how to create impressive effects with 53’s Pencil stylus and Paper app, using exclusive features like Blend and Surface Pressure.

Faux layer technique for Paper
Learn Paper’s faux layer technique and how it can aid in sketching and tracing on iPad.