Make some more samples until you get a look you like? (That sounded sort of flippant - it wasn't meant to be - some people just prefer different looks - and it does take some practice to achieve the look one wants)
Are you using the applique presser foot? It's has a raised area underneath it to accommodate the bulk of the stitching.
Did you use some kind of stabilizer on the back to help minimize puckering?
Also, when you get the look you want, write down what you did and your machine settings.