Easiest thing to do when you want to stop drawing a path is to hold command (ctrl on windows?) to temporarily switch to the "direct selection tool" (a white arrow) and click anywhere in your document. That stops the drawing, then you can release command to get your pen tool back and start drawing a new path.
Note, if you have just a "work path" be careful about clicking off of it, (deselecting it) and trying to draw a new path without REselecting the "work path" because your new paths will basically overwrite all the existing work in the "work path." It's good practice to immediately double-click the work path and give it a name so that you don't accidentally do that and lose all the paths you've been working so hard on.