Most generally the material that you are trying to cut is going to determine what type of blade that you need. A bi-metal blade would be recommended for carbon steels, tool steel, stainless steel, alloyed steels and metal working applications.
A carbon band would be used for wood, plastic, fiberglass, non-ferrous materials and things of that nature. Another factor that comes into play would be the performance levels you are looking to get from your blade, since in some cases you would use a bi-metal over a carbon type blade to get extended wear life.
A broach tooth pattern is a tooth form with a zero degree face angle. This is used in applications where you are cutting cross sections that may vary in size, being narrow in one point and wider in other points throughout the cut. Interrupted types of cuts like pipe, tubing, channel iron and angle iron, or smaller types of cross sections is when a broach tooth should be used.
A posi-tooth pattern has a more aggressive cutting action. This should be used on solid types of materials or very heavy walled materials. Positive tooth face makes for easier chip generation in these types of materials.
When it comes time to select the right number of teeth for an application, keep this rule of thumb in mind:
The 3-6-9-20 rule is that you should have a minimum of 3 teeth in the work at all times. Having 6 to 9 teeth in the work is the optimum number, but more than 20 is too many. Using this rule of thumb will allow you to get the optimum cutting performance out of your saw blade.
Bandsaw blades have very sharp teeth on them from the milling operation (this is what forms the teeth). Therefore, the teeth need to be honed before you get into production cutting. If you do not break a bandsaw blade in properly, you can damage the tips of the teeth, creating a jagged edge, which will accelerate the wear on the teeth. This will shorten the life of your blade.
To break a bandsaw blade in you should select the correct speed for the material you are cutting, and then reduce your feed pressure by 30-50%. Begin cutting at the reduced feed rate; make gradual increases as you cut 50 to 100 square inches of material; at this point you should be at your normal cutting rate.
A correct band speed achieves a correct shear angle, producing an ideal chip and more efficient cutting. If the band speed is too high, it will allow the band to ride through the material, producing thin chips and wearing the cutting edges of the teeth. If the band speed is lower than recommended, the tooth tries to take chunks of material, causing stress on the tooth, possible breakage or stalling in the work piece.
Identify the material you are cutting, locate it or material close to the same characteristics on the band speed chart and adjust speed accordingly.