Thanks, you've just saved my day.
I'll try and make a more formal guide soon, but for now, this will have to do:
How to use shape layers
With shape layers you can keep all your pen paths in one layer so it's easier to organize^^
Is there any specific
part you don't understand?
First set your pen to shapes
Then draw anything on the canvas. (or just place a point to open up a shape-layer)
Then click on the vector mask thumbnail:
Then change the pen setting back to paths:
Then click the vector mask again
Then start tracing with your pen^^ all the lines will remain in the shape layer^^