Locate the beams. They account for the majority of the load bearing. If your wall is attached to a beam, do not remove it.
Most beams will be behind the drywall, so consult construction documents or the builder, if you cannot tell. Sometimes you can tell by going into an unfinished attic where portions of the structure are exposed.Look for walls that are near floor joists. If the wall is perpendicular to the floor joist, it is probably a load bearing wall. If the wall is parallel and in the interior of the house, it is less likely to be load bearing.