Planets orbit close to the ecliptic, the plane of Earth's orbit. This makes them easier to find—a line marking the ecliptic is usually drawn on sky charts.
Unlike constellations, however, whose seasons of visibility can be predicted easily, planets are on the move. Astronomy magazines provide regular monthly guides and publish feature articles on upcoming events. Various annual handbooks and almanacs do likewise on a yearly basis. Planetarium-type computer programs can show you what is visible on any particular night.