Listen to a few ragtime recordings to get a feel for the music. Scott Joplin is one of the most famous ragtime composers. Consider listening to some of his recordings. "The Entertainer" and "Maple Leaf Rag" are two. Also, "Alice's Restaurant" by Arlo Guthrie, falls into the ragtime genre.
Practice left- and right-handed chording. Though a lot of piano music uses left hand chords and right-hand melodies, ragtime incorporates chording with both hands, very often played in unison. Also practice playing arpeggios (broken chords) on the right hand, based on the chord progressions. Often, you will play fifth chords on alternating beats. Use a piano chord dictionary to build the chord library in your head (see Resources). The more chords you know, the more versatile your playing will be.
Learn a I VI II V progression. This is a popular chord progression in ragtime, played in 4/4 time or cut time (2/4). This progression means you will play the first, sixth, second and fifth chords in a given key. Play them as seventh chords. Refer to your chord dictionary for various voicings of these chords. The progression remains the same regardless of which major or minor key you play in. The chord names change depending upon the key. You can use a major/minor key chart to familiarize yourself with the keys (see Resources).
Practice the syncopated rhythmic feel of ragtime. While the music is played in 4/4, the rhythm itself is uptempo and features beats that fall slightly off the expected beat. You will develop this feel over time. Any piece can be played as a ragtime if you give it the steady "jazzed up" syncopated rhythm of rag.