The key - short, sharp upstrokes on the 1 and the 3, playing smaller chords up the neck.
For Underneath it All by No Doubt - okay, it ain’t much but pretend reggae, but it captures the beat and is easy - you play an E by doing an open D chord shape at the 4th fret - hit it with a short, sharp upstroke twice - on the 1 and one the 3. Shift to an A by playing an F chord shape at the 5th fret - again, two upstrokes. The move that chord up two frets to make a B - 2 strokes. Then back down to A again. I am hoping that by playing these shapes with the SS Upstrokes, the sound will be familiar enough that you can take it from there…
I do a little muting with my strum hand and of course lift up my chording fingers and mute with them right after the SSUpstroke.
It helps to have single coil pickups - preferable Gibson P-90’s like on Marley’s LP Special, but that is getting geeky fast…
Hope this helps,
Scott