For regular blades, the bigger the # also means the fatter the line cut out, so if you're doing something like those dogs with the 3 toes on each foot, the line you cut between each toe will be bigger if you use a bigger # blade. I like a thin blade but I cut some angel ornaments out once with a #1 and the lines that were supposed to simulate the flowing of the wings/dress were so thin they didn't look right. Bigger blades cut straight lines easier, smaller blades can turn easier. Higher TPI gives a cleaner cut in thinner woods - just like a bandsaw blade or a handsaw, you want teeth in the wood at all times, not tooth or half a tooth. Reverse teeth are supposed to help prevent tearout on the bottom, especially if you're using plywood, but if you're cutting fat stuff they might not clear all the dust out and you could end up burning the wood. Skip tooth are like regular blades with every other tooth missing, they're supposed to stay cooler longer. If you're cutting hard exotics or metal inlay then Flying Dutchman makes a "polar" blade that works good, other makers probably do too. Olson has their chart, if you find the page for Flying Dutchman they describe what each type of their blades is supposed to do.