I recently took a t-shirt (one of those free for participating in something shirts) and made it into a summer dress for Joanna. This was a fun project!
Somethings I learned about sewing with t-shirt (jersey knit) material:
-you don't have to hem everything; jersey doesn't fray!
-jersey does stretch (that can be good or bad!)
-ruffles hide a lot! (you can't see some of my crooked seems/rough edges because of the cute ruffles)
I didn't follow a tutorial, I just laid out a dress we already had and tried to copy general size and seem ideas.
If you are looking for a tutorial, here are a few I thought looked fun:
-Happy Together: Roses and Ruffles (she shoes how to do the easy ruffles I used)
-Everything Your Mama Made and More
-Nap Time Crafters