Tips and tricks to keep it simple:
Have one chord per bar (4 chords, 4 bars) or one chord per two bars (2 chords, 4 bars).
Create a bass line that plays the root note on beat one of each bar. You can add more later.
When composing a melody, play the notes that belong in the chord it's over on the "down beat". Ex, if there is a C major chord being played, the melody should contain the C, E and G notes on the downbeats and use other notes on the off beats. The down beat is beat 1, 2, 3 or 4.
