Here is how to play acoustic guitar in flat picking style. In order to begin, you first need to get a guitar, a flat pick, and a chord book or chart. With a firm chair, sit up straight with the instrument on your lap, and place the right arm on the instrument body.
The flat pick should be held with the thumb and forefinger. Point the tip perpendicular with the thumb. The thumb needs to be on top of the last segment of the finger, pointing the opposite way.
Bring the left hand to the neck. The pad of the thumb should rest on the back of the neck. The fingers of the left hand curve under the neck to bring the finger tips to the strings. Then, press the finger tips on the appropriate strings, at the appropriate positions to make a chord.
Strum the pick on the strings. Do not hold the pick tightly. Only hold it tight enough to keep it in your grasp. Only strum the strings that are supposed to be part of the chord. A C major ope chord uses only the last five strings. For chords like this, you can drape your left thumb over the largest string to keep it from playing.
When learning a new chord, play it without looking. Remove your hand and try to play it again. Once you learn a few chords, practice changing between them without looking.
Useful groups of chords for practice are: E-A-E-B7 in the key of E; G-C-G-D in the key of G; and C-F-C-G in the key of C. These groups are found in many common songs. Practice them until you can smoothly make the changes without looking.
Short practice sessions, say thirty minutes per day, are more effective than long sessions every other day. If your fingers hurt, you can skip a day. That won’t be a problem once your callouses form.
When you get good at playing chords, alternate strums with picking bass notes in the chords. Pick the bass note first, then strum. Try putting in two strums or picking different notes to make different patterns. Keep exploring different patterns in different time signatures. Try this in 2/4, 3/4, 4/4, and 6/8 rhythms.
Make sure you have fun. Practice daily. Learn your favorite songs. Eventually, you can take the step of singing along as you play. Don’t get frustrated, as learning takes a while. But, remember that the guitar is one of the easier instruments to begin having a good time with, right away.