I'm not a veteran, and I don't play one on TV

, but I have had to pipette highly viscous reagents like VG before for work (usually 100% stock detergent solutions and VG for cell lysis buffers), and the biggest problem with ensuring an accurate measurement is that the solution will stick to the inside wall of the pipette, or whatever dispenser being used. The only way around this with pipettes, or a dropper in your case, is to give the substance plenty of time to run down the walls. I have taped many a pipette against a lab shelf over a bottle to let the solution drip out slowly and completely over the course of several minutes. I haven't had this problem recently with mixing eJuice as I ended up using a syringe at home, so it can be forced out.