Retractable blade knives are a good choice for general use, and offer the convenience of being able to quickly adjust the cutting depth of the blades plus the safety of allowing the blade to be retracted completely into the handle when not in use.
Fixed blade knives lock blades into a fixed, non-retractable position between the halves of the knife handle. This improves blade stability in severe cutting applications and allow the knife to accept special-purpose blades that are too large to retract into the handle.
Snap blade knives, like Stanley's Quick Point™ knives, are built around a blade designed to snap-off or break away in sections, providing a fresh, sharp cutting point, without having to open the knife. These knives are a good choice for light and medium duty applications, or when adhesive materials like packing tape leave a residue on the blade, making a fresh, sharp edge critical.
Special purpose blades (utility, round point, hook, scoring, carpet, linoleum, etc.) are available for a variety of cutting applications.
Always be sure that blades are properly seated in knives and that knives are properly closed and/or fastened together before use.
Never leave a knife unattended with the blade exposed. Consider using a self-retracting knife with a spring-loaded blade which automatically retracts when the knife is released.
Always use sharp blades. A dull blade requires more force and is more likely to slip than a sharp one. Change the blade whenever it starts to tear instead of cut.
Protect your eyes - wear safety goggles when working with knives or any other tools.
Always keep your free hand away from the line of cut.
When making cuts on a surface below you, stand or kneel to one side of the line of the cut.
Always pull the knife toward you when making a cut on a flat surface. A pulling motion is stronger and more positive than pushing the knife away from you, and the knife is less likely to slip.
When using a straight edge to guide a cut, either clamp it down or keep your free hand well away from the cutting path of the knife. Be sure the straight edge is thick enough to prevent the knife from "riding up" over the edge and cutting you.
Don't bend or apply side loads to blades by using them to open cans or pry loose objects. Blades are brittle and can snap easily.
When using a knife to cut through thick materials, be patient - make several passes, cutting a little deeper into the material with each pass.