When making pasta, bring the water to a full, rolling boil before adding the pasta. One of the prime causes for pasta sticking together is that the water has not yet come to a full boil. When you add pasta to water that has not yet reached the boiling point, it releases natural starches, which act like glue. Since the pasta is simply sitting in the water at the time, the strands stick together.
Give this trick a try with 2 of my very favorite pasta dishes below.