A tip one contractor passed on to me when caulking: use pieces of toilet paper to smooth it out after applying. You won’t get your fingers gunked up, and toilet paper’s cheap enough that you can use a bit to smooth off a few inches of caulk and throw the paper away.
Think I got through half a roll when sealing up a window frame a couple years back, looks great.
Snopes says this sentiment was actually expressed by Einstein, though perhaps not in this exact phrasing.