There are basically three ways that you can "shake": rotationally (pivoting around the camera's center), laterally (side-to-side, or up-down), and fore-aft movements (shifting the camera forward and backward). In most cases the lateral and fore-aft movements are negligible in comparison to the rotational movements.

Second shot: You might notice that whenever you fire a shot with your camera, pressing down on the shutter button exerts a force on the camera, which displaces its position a little bit, creating blur. By setting the camera into a "continuous shooting" or "burst" mode, you can take multiple shots at a time, and on average, shots after the 1st one will be significantly sharper because there isn't a deliberate shutter-press force exerted.

Breathing method: When using firearms, there are a number of different breathing techniques in order to aim and fire the gun steadier, and these techniques readily apply to photography as well. One common tip is to fire while exhaling, as your body tends to be more still at this point.

Multi shot: Like a lot of things in nature, the amount of blur you get in each shot isn't a constant amount, but will vary from shot to shot. While you might *average* a certain amount of blur, some shots will be blurrier than the average, and some will be sharper.

Thus, you can use probability to your advantage - with a large enough sample size, you will eventually get *one* image that is acceptably sharp and blur-free, and that's all that matters, even if you're throwing away 99 other shots that are all blurry. This is useful technique that one couldn't really practice with film, but is now viable with digital since it costs nothing to record and discard an image.