Actually, it's not that bad for your first attempt. As with everything else, it's a matter of practice and "tweaking" your stitch adjustments. Next time, perhaps try using a stabilizer on the back, just like you would for machine embroidery, because that is essentially what you are doing when you satin stitch. It may help with the puckering. Good for you for trying a new tenchnique! This is how we learn and grow