The melody of 1 Thing by Amerie runs 643 notes across 66 bars, 3:08 long in Db at 110 beats per minute. The tab sits low on the neck, mostly under the fourth fret, one note at a time — no chords to barre and no strumming pattern to keep up with. A piano backing track plays the chords and bass underneath, so the line you are learning sounds like the record even at half speed.
Prefer to strum and sing it instead? 1 Thing chords and lyrics.