We used the freezer paper method which involved some setup time cutting out letters and shapes but I think the results are much better and more lasting than an iron on. Cheaper too actually. Those iron-on things are pricey and I'm really cheap. Give me some freezer paper and a $1.49 bottle of fabric paint and I'm good to go!
Here's the one with my Edward silhouette. In hindsight I should have done him in white as the shirt is a little too dark for him to really stand out. It still looks fab though! I'm thinking I'll put him on a pillowcase next - I'm sure my husband will appreciate that.
I found a full body silhouette of Edward online and put it on this comfy green shirt. It turned out really cool and this shirt won the job of being my official New Moon movie night shirt!