Many players pick one style of play (offensive or defensive, for example) and stick with it the entirety of the match. These players are very predictable and also may become very frustrated. The offensive player may hit a few great shots, but in the long run makes many more errors than winners. The defensive player can maintain the rally and return some difficult shots, but seldom learns how to finish the point (commonly known as a "pusher").
Ideally, your goal is to be a constant combination of these two styles. You must be able to win a respectable number of points playing both in the offense and defense.
Remember, in doubles, a lob hit at the right time can demoralize your opponent, as an angle volley, a drop shot and placement. Hitting the ball hard occasionally will keep your opponent off balance which can open up the door for your "touch shots" to win the point.
In doubles, if your partner is controlling the shot in an offensive style, you should also play in the offense. If your partner is playing defensive, it will be best if you play in the defense. Remember, even in football, the team that has the ball is the offense. The team that does not have the ball is the defense. No team can stay on the offense all the time or on the defense all the time. Also, in one long point, the offensive and defensive capacity can change from one shot to the next. Be adaptable.
Good luck on the court!