One type of circular-saw blade is the carbide-tipped blade, which has a reasonable price and is much more durable than a high-speed steel blade. Purchase your blade from a reputable dealer. Select only brand-name products.
One basic rule that should govern your blade selection is that the more teeth, the finer the cut. The number of teeth is proportionate to the size of the blade. For example, an 8" blade with 35 teeth will give about the same cut as a 10" blade with 50 teeth. Some blades, such as planer blades, tend to wobble slightly, and this will affect the cut. Therefore, a set of stabilizers is recommended. These stabilizers are like large washers that are slightly concave and fit on both sides of the blade to stabilize it.
There are also blades, generally 10" or 12" in diameter, that have a very shallow cutting tolerance. These blades are very thin for the first 1-1/2" or so. And then become thicker up the arbor hole. These blades are meant for cutting plastic laminates, etc.
There is a group of specialty blades that are designed to be used in particular woodworking situations. Included in this group are blades with 200 teeth that are used for plywood and give an extremely smooth cut. Unless you are in the woodworking business and set up for production, they probably won't concern you.
Following are some types of blades that are recommended for use in the workshop. A combination blade is a general-purpose blade that will give fairly clean crosscuts and rip cuts. A crosscut blade, as its name implies, is the blade best suited for crosscutting. It generally has more teeth to provide a smooth cross-grain cut. A planing blade gives an extremely smooth crosscut, but is very thin and should not be used for ripping or very thick material. A rip blade generally has fewer teeth than other types of blade because it faces less resistance as it is used to cut with the grain of the wood.