Thanks for the C&C! How do I make the focus sharper? I tend to do most of my shooting in portraiture mode in fine JPG on the highest file size. Should I move to a RAW format?
Remember that .jpg is a lossy format, so if you're going to be doing any significant post-processing you're going to lose information. I would suggest shooting RAW+JPG. The format has nothing to do with your focus however.
Factors effecting focus: (1) The single most common focus issue is NOT focusing on the intended point. Check your camera's manual and ensure you know how to control the active focusing point(s). Make sure that the active focusing point(s) are on the parts of the scene you want in focus (ie: in a portrait, make sure the focusing point is on the eyes and not the wall behind the subject's head). (2) "Things" on lenses - filters, especially cheap ones can have a HUGE impact on IQ. Take 'em off unless you NEED them! (3) Aperture: Using a lens wide open or nearly so (smallest f#s) may contribute to a soft image - even the best lenses aren't as sharp at their largest aperture as they stopped down part-way.
Also make sure that you're using a shutter-speed appropriate to what you're doing. If you've got a 400mm lens on your camera, a shutter speed of 1/60 is probably not going to cut it, likewise, if your subject is a fast-moving car, you're going to need to be north of 1/1000 of a second if you want to completely freeze all motion.