Another simple trick to nice looking silicone :
Apply the bead of silicone to the clean and dry joint.
Spray the bead with water from an old Windex bottle or similar.
Finish the joint by spraying your hand with water and using the backside of your thumbnail
to smooth the joint and remove the excess.
The excess silicone won't stick to the wet areas of the panel or to your thumb.
Once you get the hang of it you will make a perfect joint every time.
I gaurantee, if you try this once you'll do it forever.
A job worth doing is worth doing well.
I enjoy compliments on the workmanship of my setup as much as ones about my fish.