I started by using Lucy's tutorial for her mandala wheel. You can find the pattern at
Lucy also linked to some of her favorite patterns. I loved the little spring mandala, found here
I made some other mandalas, without a pattern. You can find a lot of ideas on pinterest, or you can just start crocheting rounds and see where the patterns and colors take you.
I'm using up the acrylics and cottons from my yarn stash, dreaming of making some sort of colorful wall hanging. For now, the completed mandalas are resting in a basket. I would love for you to leave me any suggestions in the comment section. And, please check back for my mandala updates.