Learning to use Illustrator to digitise my patterns was like giving birth to a country. I pretty much hated it and kept going back to Inkscape. Then I discovered Sew Heidi and her amazing tutorials and now I love Ai a lot.
The trick to learning anything is to find a tutor or teacher that you click with. It also helps if you are learing from a person who works in your field. Then you can focus on the processes you need and not the enless stuff you don't. Sew Heidi has a lot of great tutorials and downloads for the fashion designer. Give yourself time when you visit her site because you are going to be hanging out there a while.
If you want to learn how to use your pen tool, Heidi is your Gal and this tutorial is your new best friend.