Well, you've certainly given yourself a challenge with this one! Particularly as you've never appliquéd before. Why not put it to one side until you get a little practice in? Heart shapes are ideal until you get the hang of it and you'll be able to decide whether you prefer zig-zag or blanket stitch. Whichever one you choose, you'll need tiny stitches. Did you notice how the one in the shop was done?
If if you just want to dive in, you could try a simple straight stitch. Although I've never done it myself, McKenna Ryan straight stitches all her appliqué.
Good luck!