The main reason for using you tripod is to steady the camera. No matter how well you brace yourself, and control your breathing, and press gently on the shutter button, your camera will move. On a bright, sunny day with a short lens the exposure time will be sufficiently short that the movement might not be captured, but longer lenses, small apertures and dull days conspire to give long exposure times, long enough to slightly blur your picture. Even on a fairly bright day, if you are using your polaroid filter (you probably should be) exposure times can sneak into the don’t-handhold range.
The general guide for hand-holding is to take the lens focal length, add a half if your sensor is APS-C size, and treat it as a fraction of a second. For a 100mm lens adding a half gives 150, so you should only hand-hold if the exposure time is faster than 1/150th of a second. If you are using shake reduction you could do at least two stops better, and so get down to maybe 1/30th.
The tripod should of course be reasonably sturdy, and nice and light for ease of transport. These two mutually-exclusive objectives will require, as in so much else in photography, compromise. And since you are using the tripod to minimise shake, don’t touch the camera or tripod while taking the picture. Use a cable or remote release.
But use of a tripod confers another benefit, time. You have to set up the tripod, check that the camera is horizontal, adjust the height, remember to turn off the shake reduction – things that take time, during which you are more likely to notice if there is something not quite right with the composition, or the viewpoint or the exposure – you have more time to get it right.
The tripod is of course also a great prop for scrambling over the rocks on the annual trip to the Saltee Islands.
Picture from http://www.picgifs.com/