K10d sharpness issues (or human fault!)

Hello!

I have a K10d and i cannot take any sharp picture. In the beginning i had the 18-55 kit lens and i thought that the fault was on the lens quality but after that i bought the DA 35mm f2.4 and still i get soft and blurry pics.
I shoot on manual, with speed over the 1/60 and f8 aperture, ISO 100-200 but still i don't like the result.
I am not very experienced in photography, probably by 99% the fault is mine but in the back of my head i believe it's the camera or the sensor or the known back focus issue of k10d. How i can check if the camera is ok by myself before taking it to the service? Which are the best camera settings (colorspace, sharpness etc) except the image quality i have already set to highest?

Thank you in advance!

Stratos

A sample image would be helpful so we can see what you think is unsharp.