1. Shoot in RAW and always sharpen in Lightroom from 50 to 100 depending on the image. If you shoot in JPEG your camera sharpens the image and you may not like the results your camera’s software comes up with.
2. Do not shoot a scene that is beyond the dynamic range of your sensor.
3. Exhale slowly while shooting and shoot between heartbeats.
4. Shoot at a fast enough shutter speed (1/focal length or faster) with your lens set at a mid range aperture; f/6.4 f/8 or so.
5. Shoot at ISO 400 or much less if you can.
6. Do not underexpose and try to push the shadows in Lightroom, you will have too much noise. I do this way too much because I am paranoid about blowing out detail by overexposing my shots. This is a worse transgression than underexposing your image.
7. Do not use a zoom lens. Use a prime. Always use a lens hood, always.
8. Don’t use a UV or clear filter over your lenses. Use filters only if you must (i.e. ND, polarizer, etc…)
9. Make a tripod with your arms and forehead and a wide stance with your feet or lean up against a building, fence, tree, car…. or get on the ground.
10. Pan with your subject if it is moving. practice this technique.
11. Make sure everything is clean.
12. Focus manually or check your auto focus system using a tripod and take several shots in manual and auto focus to see how accurate you auto focus is working. Some cameras let you adjust your auto focus.
13. Use back button focusing to focus and set it up for single point focusing and lock focus BEFORE you take the shot.
14. When shooting people; always focus on the eye that is closest to the camera.
15. Shoot multiple shots and look at the images 1:1 in LR and pick the sharpest ones.
That’s all I can think of.
test your lens: http://bobatkins.com/photography/technical/lens_sharpness.html