I'd like to learn "Under The Bridge" by The Red Hot Chili Peppers, and during the verse part, there's a mix of single notes (triplets as I recall) in between the chords. How do I pick/strum that? Are there exercises that are good for developing skills to play songs like that? (Songs that mix strums and individual notes?)

It seem like the strumming exercises I see online are all extremely basic strumming patterns.