Why a Tripod?

To some the tripod (or monopod) is looked on as a necessary evil, but I really don’t believe there is anything evil about it at all. Very often it will get taken out on a photo shoot, just to be left in the car boot (trunk). But tripods should never be underestimated, there are times when you simply cannot do without it. So if you think you have too much to carry and there is a long trek from the car to the shoot, I’m sure the little wife will only be too happy to carry your tripod (says me, looking gingerly now over my right shoulder).
Yes, they are heavy and can be cumbersome at times too, but don’t look on the tripod as an extra burden. It should be the first thing on your list to pack - not the last. Apart from the camera of course!
I find, that once I have the camera mounted on the tripod, it gives me the (hands free) freedom to move about the scene and mentally compose my shot. Then, all that is  required, is simply to make the necessary adjustments and shoot; and my hands are free again to contemplate the next viewpoint or a different angle.

When using slow shutter speeds or shooting in low light, you cannot do without your tripod. I know, you can always lean it on the side of the car or a tree, but these sorts of surfaces can only restrict and limit your shooting angle or view point.

If you wish to shoot waterfalls and achieve that dreamy, misty look to the water like the pros, where your shutter speeds need to get down to at least ¼ - 1/3 of a second and slower, you will definitely need a good sturdy tripod, because the risk of camera movement is greatly increased at those low speeds. Also, if you want to take panning shots of a moving vehicle and have the vehicle in sharp focus whilst the background is all streaky in the depiction of movement, a good sturdy tripod is also essential.
While you have the ability to use slow shutter speeds this then allows you to set much smaller apertures, allowing greater depth of field in your pictures. You can in fact shoot at any aperture you wish and with small apertures, coupled with your tripod, you can produce some great accurate panorama shots as well. Although with these shots you will need to ensure that your tripod is level.
If I have finally convinced you now to go out and buy a tripod, give some serious thought to spending a few more dollars on a good heavy duty type. I’m not going to mention any brands here, but you don’t really have to go over the top. Simply explain to the sales assistant that you want a good heavy duty one. You need to consider weight and strength, but you don’t want to pay more than you can afford. If it is too heavy you are not going to be encouraged to take it anywhere, but on the other hand, if it is too light, it’s not going to support your camera properly.
I have seen one that converts into a monopod by removing the centre stem, which then telescopically forms into a monopod/hiker's stick. very ingenious!
I use a heavy duty steel one to put the heavy gear on, although I am still able to carry it to most places. I also have a light weight one that I mainly use for an added lighting support. With an adapter, I can fit the external flash unit onto it, by the use of a sync lead.
A few quick tips to help you get the best from your tripod.
Always spread the legs fully. Common sense really, it's going to be more stable the further you spread the legs. Some tripods, like mine, allow you to spread the legs past the normal stops to get you out of trouble in tight situations. Only use this facility when it's really necessary.
Use the minimum height you need. Don't go higher than you have to, the higher you go the more wobbly the tripod will be.
Extend the legs rather than the central column. The central column should only be used for fine adjustments, it is not as solid as the legs.
Adjust the height of the legs before spreading them. It's the only way to make sure that the legs are all the same height. This will give you the best chance of the camera being level. However you still need to check it by eye or with a spirit level.

Here's a tip:
If you are a bit light on in the ready cash department and you only possess a light weight tripod and you are off on a field trip this coming weekend, fashion a piece of strong fencing wire into a hook that you can attach to the centre stem of your existing tripod and take along with you on your shoot a fairly strong plastic shopping bag or similar, so that when you get to your destination, you can attach the hook and suspend the bag from the hook with some rocks in it. This will weigh down your tripod and provide a sturdier base for your camera. Especially if it is windy where you are going and you can never be too sure that it won't be.