Start by changing your SSH port from 22 to something else. It stops 99% of automated attacks. Beware that it is obscurity, not security though. That said, it do

Start by changing your SSH port from 22 to something else. It stops 99% of automated attacks. Beware that it is obscurity, not security though. That said, it does help clear some of the "noise" to focus on the other 1% of attacks where the attackers are actually a bit more sophisticated than a simple script.