Im not much of a fan of syrups, but I would say explore some single origins, find out what distinctive flavours they can carry. For example, some coffees are known for their berry and fruity like flavours. Others for their citrus acidity. Others again for their chocolate or sweet notes. Find out what it is that compliments those flavours and run with that.
I would also watch over some old barista comp videos and have a look at their sig drinks. Dont copy, because thats not cool, but use them as inspiration for what works and what doesnt.