My last Advantage application was disastrous as I did it in a hurry and got it more on the side of the neck than the back. Jaffa ended up with it all over his front, and I ended up chasing him with a bowl of soapy water to wash it off (and ringing the vets to ask what I should do).
I've found the best way to get it on the skin and not the fur is to resist the temptation to lift the pipette from the skin to check whether it's all out. The time before last I just parted the fur, placed the pipette against the skin and squeezed the tube but didn't lift it even a fraction of a mm until I'd squeezed the contents out. I got virtually nothing on the fur and for the first time didn't end up with an area of manky fur where it was applied.