If you are getting tear out, you should also look at the grain direction. If you are planing against the grain, it will tend to pull the grain up and cause tear out. Sharpening and tuning the plane will help, but probably would not eliminate that. Sometimes simply try going in the opposite direction to see if it works better. If it does, you probably were planing against the grain. Also, some boards may have grain going in all kinds of directions, so you may have to change directions often. Having a slight (emphasize slight) camber to the iron will also help so the plane will not be prone to dig in on the corners of the blade. Also, you may be trying to cut too much. For smoothing, you want very fine, thin shavings. As for sharpness. I used to think that my planes were sharp, till I had the chance to use a plane that was owned by a gentleman that I consider to be a master craftsman. I found out that my idea of sharp, was not really very sharp. At the minimum, you should have a mirror polished edge and about 1/2 inch of the back should also be polished to mirror finish. Also, if you couldn't shave with it, it aint sharp enough.