A bit of preplanning and masking off and there are no reasons to make a mess. You lay down the bead, then smooth it over with your finger, work determined and try to only go over once, if you start fiddling with bits that don't look perfect, it goes all rough and nasty.
a.) mask (at least 1 inch tape)
b.) place the silicone bead down with a caulking gun
c.) smooth it out with your finger
d.) clean your finger
e.) pull off the masking tape
f.) clean your finger again, and wait at least 24 hours for curing.