One of the main differences between beginners and PRO photographers is, that PROs always get sharp and crispy (mmm) photos. To get great looking images you need to consistently nail sharpness.  There are few things that you need to keep in mind, and a few techniques that you will have to learn to achieve great results.

Focus. The first and most important is nailing your focus .  Whatever you do in camera or post, if you don't have your focus right you can never have a truly sharp image.  We have a great article on focusing, take your time with it and make sure you understand it.The Sweet Spot.  Every lens has a "sweet spot", this is usually a range of settings( if it is a zoom lens, it is combination of zoom and f/stop) in between which you will get the best results out of that lens.  Spend some time online and get to know your gear.DOF.  Unless you have a top of the line Canon or Nikon (or some other great brand) in combination with the fastest auto-focus lenses available, you will have to allow enough Depth of Field.  More DOF will guarantee you that your subject is in focus.  The "sweet spot" of most lenses is one or two stops after the largest aperture of the lens.Shutter speed.  Shutter speed is almost as important as focusing, you can't get sharp images, unless your shutter is fast enough to freeze the motion. How fast is fast?…it depends on the situation, but, for action 1/500th of a sec is pretty much the minimum.  Also make sure that your shutter speed is at least twice the focal length.  For example if you are shooting with a 200mm lens, your shutter speed needs to be 1/400th of a sec if you are holding the camera in your hands.Sharpening. Sharpening in post production makes a huge difference , but you need to make sure you have all the other ingredients for a sharp image before you apply software sharpening.  Sometimes you can save an image, but don't count on it.Master every one of this tips, and then put it all together for amazing looking sharp and crispy images.