When I started work on mine, the bed leveling and radius (Delta-only issue) were horrid, and my erstwhile assistant was fond of using a LOT of glue stick, which sort-of made things work, though in many cases with no first layer extrusion.
As I sorted things out, I found an apparent bug (Repetier Host (Mac) and Marlin 1.1.0-RC8 firmware - not sure which side the apparent bug is on, really, but I'd guess Repetier) where setting the first layer by percent lead to no extrusion, and setting an actual width/height it extruded. I also got the bed level and radius sorted so the first layer settings actually applied to most of the print area, rather than being wrong for most of it.
Finally, we sorted out some temperature issues (wrong thermistor type setting) and then found a fairly large discrepancy between the heater block and the nozzle (screwed into it) temperature. I now lay down the first layer (PLA) at a purported 240°C, based on a number of trials at different temperatures (which might change with a different batch of filament, I guess) and the rest at a purported 215°C. I set the first layer width to double the height so it's really laying down some plastic. An excessively LOW first layer height also causes problems (as there's very little plastic coming out if the layer is very low, even if you set the width wide.)
My bed is not heated and is plain glass, but I now get reasonable sticking with a very thin layer of gluestick (I put a dab on and rub it around with a little bit of water - it's barely visible.) With a coated heated bed that sticks to rafts, I think you'll just need to work on your first layer settings (including a level bed) and should not need to worry about glue at all.
