Just as the bass walk is a “classic” for rock and roll, the lower 5th is very common for folk songs (and polkas!). The normal method is to play the root of the chord on the first beat of the measure and the lower 5th on the 3rd beat. As it turns out, the lower 5th is on the same fret as the root, one string lower (so you have to play the root on the A or D string. Here are some examples showing a couple of ways to play it.
So now you have even more tools to work with. As a beginning bassist, the trick is to apply these tools to the different songs you learn. The more you play, the more you will see that most of these tools will work on many songs, and you will be able to sound very good on a song you’ve never played.
Good Luck!
