Try and track suspicious players; this could potentially reveal that they visited a role that died the next day. Just make sure they aren't a Veteran baiting.
The Tracker is mostly a team player that works with other roles to find out the roles of people being tracked. Try to find other TownInvestigative and TownProtectives to track down evil roles that don't kill immediately.
If you know who the Doctor is and you think that you have found a Poisoner, then it may be a good idea to whisper who the Poisoner targeted. This way, the Doctor could heal the poisoned player. Of course, most players will say that they are poisoned so this strategy may not be useful. However, if the player is blackmailed, this will work as an effective backup plan.
If you track the same person each night and they keep visiting different targets, try to communicate with a Sheriff or Investigator to see the target's investigation results. If the people that are being visited show up as an Arsonist, then the person you are tracking is an Arsonist.
The Tracker is essentially a reverse Lookout, so strategies for that role work well for this role - simply inverted.