When most players learn a competitive serve, they are usually taught to serve underspin.  This sets up a push from the opponent, which is then attackable and leads to favorable situations for the players.  While this mindset is good for up and coming juniors who need to learn how to attack underspin, it is not always the best way to start points for more advanced players or players of a certain skill set.  When I play any opponent, I go in with the mindset that most players will serve underspin to me and I will also serve mostly underspin.  While this may have been not the best idea when I was training many hours a week, it was a strategy that I made work with hours of repetition.  

Yet these days when I fit in practice sessions into a full courseload, I find that these patterns are too predictable and players who have been playing more than me have no trouble in giving me deep cuts or drop shots that I have trouble attacking.  Players generally expect an underspin serve and are all too happy to take advantage of one.  Serving topsin or nospin is thus very favorable, not just as a change up once or twice in a game but on almost every serve.  A well placed nospin serve is very difficult to flip, and often elicits a return that is either high or weak and easily attackable.  Players also cannot generate as much spin off a nospin serve, so it is easier to lift when looping.  Serving topspin has great effects too, as players generally do not want to flip too hard because they are afraid of flipping off the table.  I have found that even serving obvious topspin over and over again does not bring about more aggressive flips from the opponent, as they are not used to seeing so many of these serves in a row.  After doing this through a couple practice matches, you will be able to notice patterns off the serve return that you can then use to your full advantage and thus create more favorable situations.  Have fun, and good luck!