Acrylic paints tend to stay on fabric much better in my experience than puff paints.
You can get applicator tips to use to outline around the appliques raw edges, they usually are right in with the small bottles of acrylic paint, if you wanted to do this.
I found a package that had 3 plastic tips and also 3 metal ones with different sized openings.
I have also seen where people outline the areas with stitches, and then fill in with inks or paints.
There are inks out there that you can use, or mix with clear aloe vera gel to keep them from spreading so much too. Lots of techniques for this, I have spent hours on YouTube watching videos on using inks on fabrics.
It is all up to you, and the look you are trying to achieve.
Practice on different fabrics, more loosely woven may not work as well as more closely woven. :D:D:D