I work for a big tech company that produces documents to other businesses, when we send these documents we often encrypt such documents with TrueCrypt.

In my department I recently wrote a shell script to create a TrueCrypt volume, assign a password (or a random password if none supplied), mount it and copy the files we want to it and unmount it. It would also create an ISO for us to use so we can burn the Truecrypt volume to a CD/DVD. There are various amount of prompts that take in user input. The project took me less than a few days to complete. I had barely any shell scripting experience before hand and now I'm getting asked to work on more projects using bash. If you're really into learning I would suggesting picking a project to do (for example with truecrypt, setting up an apache server, what have you) and see how far you get.

Basically, I wrote a script to automate the creation of Truecrypt volumes (with client media) and it has been working out great. I only learned shell scripting because it would improve my job and other people's job in the same department.

Edit: I really don't have any resources, when I was stuck on something I just googled it. Most of the time my answers would come from stackoverflow.com. That website has some really good programmers on it.

tr;dr pick a project, focus, do it.