Air drum. I know most people would tell you to start songwriting with drums, but try writing something, then losing yourself in it and air drumming. Listen to MIDI tabs (Guitar Pro for example) of artists you like and isolate the drums. One thing that makes anything groovier is syncopation, and simple polyrhythms can sound surprisingly good. Pay close attention to what tension level you're trying to achieve in each section of a song and vary the drums accordingly.

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