Getting proper stick is a function of the following factors: 1) correct first layer height; 2) sufficient heat; and 3) properly preparing the surface.
Before going any further make sure the bed is level and the left/right adjustment is correct.
After leveling the bed, make sure the first layer is going down properly. In Slic3r, make sure that you are using at least two loops to go around the part (essentially to prime the hot end) and run the first layer at a slower speed than the remainder of the part (between 50-80%). Once printing, look closely at how the first layer goes down. The thickness of the first layer should be somewhere between a flat surface and a tube. Maybe the best way to describe it is as a pancake. If the bed is level, the thickness of the first layer should be consistent throughout the first layer. Another trick in the latest version of Slic3r is to increase the first layer percentage (to say 200%). Finally, on large parts specifying a “brim” (through Slic3r) also tends to prevent lift-off.
Heat is also an important factor. Too little heat and the parts will NOT stick, no matter what you do (for ABS). Too much heat, and the parts will stick well, but the sidewalls will have an hourglass shape (from heat warping). The heated bed is hardwired to the power supply. At 12 volts, the bed will get to about 110 degrees C. This value can be manipulated by adjusting the voltage on the power supply (be careful). The more voltage, the higher the temperature, the less voltage, the lower the temperature.
Finally, you must make sure that the surface is prepped. ABS will not stick to glass. The best solution we have found is to coat the glass with PET tape (or Kapton tape). When printing, make sure that the PET surface is facing up. Also, we have found that applying a thin layer of a mixture of ABS and acetone to the surface will further increase grip. Mix the ABS into the acetone so that the liquid appears cloudy. Too little ABS and the solution will not increase stick, too much ABS, and the parts will not come off.