When I came across the title of this class, I knew it would be great for me as I made most of the common mistakes while making a repeat pattern. Although I don`t use Illustrator, I found this class valuable for me as same principles could be applied when working with Photoshop. 

I have created this pattern recently. Here is the old version before all the tweaking. 

Vertical lines are even more visible here.

I have changed the order and size of some leaves and re-arranged the pattern. I hope it looks more balanced now. 

Delores, thank you very much for covering this topic and for your explanation of various design mistakes and how to fix them.

Here is my edited version.

If you can see how it could be improved further or if you can see any mistakes, please let me know! 

Thanks a lot!

:-)