A guitar riff, is a instrumental hook or motif that adds interest to the listener.
They are usually simple. The most effective sometimes only a few notes.
These are some examples of the greatest guitar riffs of all time.
Your songwriting guidelines
About cute animals
Keep the chord progression simple. There are a lot of elements to combine. The more comlicated the more difficult to put the elements together and more difficult to listen to.
10 Words maximum (slogan, a hook aline that you want to repeat)
30 words maximum (The verwse, it explains the title)
Riff (2 chords maximum) (Keep it simple and conjunct)
Must be memorable
Use Hookpad to help you
Refer to the lyrics lists you have used