I cut out a heart shape. Here is the pattern I made. If you can get it to print from here then go for it. It should be about 2.7 inches across at the widest part.
I cut out 12 little heart shapes for my shirt. I used this fabric, and this shirt that I snatched for about $6 from old Navy. I recommend using a scoop neck T-shirt, because they are universally flattering, and have a nice little spot for the heart petals.
Next, I zig-zagged around each heart. This doesn't have to be perfect, and you will still have some little frayed pieces hanging out, but it will keep it from totally unraveling in the wash.
Then, I placed my pieces roughly how I wanted them (although I ended up switching them to other side since I normally wear my purse on my right shoulder). The edges should overlap a bit so the will kind of fold up on each other.
After getting them all pinned down how I wanted them, I sewed each heart down with a straight stitch following generally the dotted lines on my heart pattern. Make sure you don't catch a neighboring heart in your stitch.
And that's it. Lovely!