To get that warm, organic acoustic guitar tone I am using my thumb to pick out the intro riff and strum the chords. I’m also picking closer to the bridge of the guitar for the strumming. These are the guitar technique’s Bob Marley used, as you can see in the video clip below.
I also am keeping my right hand in constant motion to keep the rhythm flowing. This is important to feel the pulse of the music and so your playing doesn’t sound stiff.