What I have learned is to spread caluking in small bead size and small lengths. Wipe your finger in water and then swipe the caulking into the edge. It will smooth out. At the end of the trail, start again and using small beads and lengths.
If you put a large bead, the excess will smear the side while smoothing.
Another option is to buy a plastic smoother that may be available at home stores. I have never looked into it.
But the key is small beads and small lengths.
Also a drip free gun is handy. It releases the pressure the moment the handle is let go.
Good luck. If you messup, after drying, take a blade, carve it out and go at it again.