How to Play the Guitar Using Alternate Picking
Alternate picking is the right-hand picking technique that uses both downstrokes (toward the floor) and upstrokes (toward the ceiling). When you learn how to play the guitar using alternate picking, you can play rapid, successive notes in a smooth, flowing manner. Single notes that you need to play relatively fast almost always require alternate picking.
The reason that you can play faster with alternate picking is clear. To play two successive downstrokes, you’d need to bring the pick back up above the E string anyway. But by actually striking the string with the pick on the way back up (using an upstroke) instead of avoiding the string, you can greatly increase your speed.
To play a downstroke (the open-bottomed box symbol above the tab), Start with the pick slightly above the string (on the ceiling side). Then, strike the string in a downward motion (toward the floor).
To play an upstroke (the V symbol above the tab), start with the pick below the string (on the floor side). Then, strike the string in an upward motion (toward the ceiling).
Take a look at the following figure. The melody in the tab staff is actually Old MacDonald Had a Farm. Try playing the tune slowly, using only downstrokes. Then play it faster by using alternating picking, as the symbols above the tab staff indicate. Here a pick, there a pick, everywhere a pick-pick. . . .