During the matches themselves you'll usually just see some text that lets you know what is going on, but every once in a while you'll have to step in and decide what your player does next. You'll have to decide if he should pass the ball, shoot a goal, or simply try to steal the ball from an opponent. Whatever it is you do, you better do it right as it'll improve your relations with your fans, teammates and the coach, as well as help you win the match.
While not playing in a match, you can do many other things. From negotiating with sponsors so you get paid more money per match, to buying a whole bunch of stuff that gives you a nice lifestyle, or playing at the casino in the hopes of getting even richer.
All of this will affect different parameters that improve your player's performance on the field. Happiness, as well as your physical shape, and shooting skills will all help define whether you are a better or worse player.
New Star Soccer is a very fun game that, in spite of giving the initial impression of being a bit childish and simple, provides you with an addictive game play that is not easy to find, as well as the possibility of many hours of gaming. A must-have for those who like soccer games.