When drawing straight lines in Photoshop, and I'm not snapping to the horizontal or vertical, doing diagonal lines by clicking on the start point and then shift clicking on the end point is hard to do if I need the line to run through several points.
Is there a way that after clicking once and holding shift, a line guide will appear to show me where my potential line will appear?
The option you want enabled is called Rubber Band.
The Rubber Band option will preview the path before it's laid down. No need to hold down any button at all, it will preview the path at all times. (It will also preview where the line will be even when you hold the Shift button.)
The Rubber Band option is located under your Pen Options when you have the Pen tool selected.
For further reading, there is a fantastic article by Smashing Magazine on Mastering Photoshop With Paths.
