Clamps, you can never have enough of them. That is one of the universal laws of woodworking. You will always run into a situation where you either need more clamps or the ones you have are too short.
As you start building your clamp set, you will need several different styles. I’ll just touch on the basics and what works for me.
Small F-style clamps are designed for small work. The decent ones will have a rigid metal bar (usually chromed or black) with a fixed arm on the end. The piece that slides on the bar will have threaded rod with a pad on one end and a handle on the other. When using you will want to turn the handle until the pad is just about all the way back. These are usually pretty bullet proof, no matter who makes them, however, the cheaper brands will flex under pressure. One good way to check the quality is if you can flex the bar, don’t buy it. I have a lot of these, mainly Jorgensen and some from Rockler both work equally well.
Pipe clamps are one of the best values in the market today. They are designed to be attached to either black iron or galvanized pipe. They come in two sizes based on size of the pipe. The pipe used will be in either ½ or ¾ in pipe. The clamp comes in 3 pieces, the head piece, the adjustable foot and what looks like a spring. You can buy the pipe in various lengths from the local box store and it will come with the ends of the pipes pre-threaded. The head piece will screw on one end, the foot piece will slide on the other (note, there will be a spring loaded lever that will hold the foot in place, it can be tricky to slide on the first time) and lastly the spring will screw on the opposite end. This is to keep the foot from sliding off the clamp. The nice part is if you need a longer clamp, you just need a longer pipe. In my shop, I have several sets in both sizes.
Parallel clamps are very popular today. They are distinguished by the large plastic boxes covering the head piece and the foot. They work very similar to the F-style clamp in that the adjustment is made on the sliding head of the clamp and the foot is stationary. Parallel clamps excel in helping keep work square during glue up. The large plastic covers also help spread the force of the clamp over a larger area and minimize clamp marks that are a common problem with F-style and Pipe clamps.
There are several other style of clamps but these tend to be more specialized. There are band clamps that are very similar to cargo tie down straps; wooden parallel or hand screw clamps are large wooden blocks with two threaded rods to adjust the clamp; and Spring clamps which work like a lot like spring loaded clothes pins.
A few things to keep in mind when buying clamps; a lot of the very cheap Asian clamps are poorly cast and have weak metal. I tried a set of four and three broke when put under normal clamping pressure. I also avoid aluminum bar clamps. My wife gave me a set for Christmas one year and they didn’t last too long. There are several good brands out there from which to choose, it doesn’t matter what the brand is as long as it is well made.
Shopping Tip, buy clamps in sets of four. You almost never use and odd number of clamps during a glue up.