Guys, some comments here are incorrect. LOWERING the bed temperature actually helps very often.
Try this: 60C initial layer, 50C subsequent layers. What lowering temperature does is this. It does not improve the "adhesive" properties of the material (actually makes it worse), BUT, it makes the bottom part more rigid on it's own. This helps reduce warping IN CERTAIN TYPES OF MODEL geometries, e.g. with corners.
If you increased bed temperature and warping got worse - try decreasing. You may be surprised.
Also, increasing print speed is known to reduce warping in some cases.