I cover it with PVA-glue mixed with water at a ratio of around 1:1. This is the cheapest and easiest way I have found to make the print stick to the glass. PVA-glue should be available in any store that sell tools and material for carpentry and such.
This printer was a test to see how much I could do with it, it wasn’t to expensive but the 3D-printed parts are breaking and the factory fitted Mk8 hotend / extruder combo broke only a month after I got the printer. I would totally recommend it to someone who want’s a cheap printer but if you don’t now how to build and rebuild things it is better to go with a Wanhao Duplicator i3 as the first machine.
I am not sure yet about what the new machine will be but looking at some Delta printers that have lots of printable parts so I can print most of it myself. I have read that those printers have a much higher printquality than the i3-clones have.