Getting sharper? Take 2 greenfinch with Pentax

Using a Pentax KX and getting very frustrated with my inability to get sharp images. Does anyone else have this problem? Very hard to know where you are focusing, even with spot focusing and VERY hard to get a really sharp image. I'm using a Pentax 75-300mm lens SMC Pentx FAJ. m would be very interested to see images of anyone using a similar camera.

This image was taken at f11 at 1/100 - should be fast enough for reasonable depth of field etc?