After a bit of experimenting, I have found what I believe to be the very best, most consistent method to stop warping of ABS & Nylon ( possibly other plastics.)
I use Blue Painters Tape on heatbed, then brush on a thin layer of Elmers Washable Clear School Glue. In my opinion it provides the perfect adhesion properties. ABS and Nylon both stick great to it (even if your bed is not perfectly level!). Equally impressive is the fact that when you remove the print, it will pop off without excessive effort. I can promise you will not be sorry trying this.
I tried the glue on kapton tape originally,l which worked well, but not as good as on the blue tape. If you try it on bare glass, please tell me your results. I haven't tried it simply because currently the blue tape and glue is working so good.. and I suppose sometimes i'm lazy ;)
You can dry it faster by heating Print Bed to 45 degrees.
*STL download is a dummy file, unless you want a printable set of instructions :P