43 years of glazing, building solariums etc etc and all I ever use is a bare finger. No spitting on it, dipping in anything at all. Pro results on thousands of projects. I keep a shop towel nearby to wipe my finger on.
The whole key to a good result is putting a tiny bead on and then tooling it with your finger. If it squishes out around your finger you have laid to heavy of a bead on.
And to do that you cut the tip of the tube so it has a tiny hole, not halfway down so it's the size of a garden hose.
Doesn't matter if I'm using silicone, butyl, polyurathene, elastomeric, polymer or any of the others. I do them all the same.
Tiny bead is the key to a good finish.