Dan,
not to worry! Mo's Zim looks better than almost everyone else's!
practice, practice.
i am zimming my first vehicle too.
i think every new surface i do is a bit better than the one before,
but i have a long way to go.
my new discovery is to take one of the toothpicks that has round ends, but a
square center cross section, and cut it down so just the square part is left.
(probably a wooden match stick w/o the head would work too)
this makes a nice close quarters 'trowel' to even out the putty and to get a nice
thin layer before using the tool.
keep after it. you'll just keep getting better.