Not bad. Make sure to have your camera perfectly perpendicular with the glass.
In your first clam picture, you see how it looks funky? That's diffraction caused by not having your camera at a perfect 90 degree angle from the glass.
You'll get a lot clearer pictures if you can do that. If you use a lens hood, you can just rest your camera right against the glass. Not only does that make it a perfect angle, it also helps you hold the camera really still, making it so you can get away with not having a tripod if you dont want to use one.