The answer to your question is Chalk. Tailors Chalk or even everyday school type chalk.

You can lay-out your pleats with it. You can mark the bottom of your Fell and where your waistband strip is going to be. You can make tick marks where ever you want or need.

Heck, you can draw a Tartan pattern if you want and if it would help. But I find that marking the edges of the pleats for the vertical and a couple of ticks for the horizontal keeps everything lined up perfectly.

Sharpen the end of your chalk with a knife or a piece of sandpaper to get nice sharp lines.

When your done, slap your fabric with your hand and the chalk comes right off.