With the ender 3 i found it difficult to print anything direct onto the glass plate even with adhesion aids. In the end I ended up using a thin sheet of Tufnol sanded to remove the glossy surface clipped on top of the glass bed. A smear of PVA glue stick and it works every time for PLA and PET-G. For ABS a coating of ABS milk (10% abs filament in Acetone) works the magic for the filament brands I use but there are brands that I have failed to print !!!!..
As you know the leveling settings are crucial in my case with the Ender 3 about 0.075mm is right and about what you get with a piece of 80grm printer paper or better still get a piece of metal shim stock. Here in UK shim stock can be obtained on EBay from model makers suppliers mostly it seems to be sold in thousandths of an inch 3thou is right 0.076mm.