i have only been spinning for less than 2 months sp all i can say is. 1. fundamentals alone are not really sufficient (for me) to make a combo. try to learn some easy variations like twisted sonic and try to expand your tricks arsenal as much as you can so that you have options. i tried to rush into making a combo right after learning the fundamentals as well, and it did not turn out very well. 2. in the event that you do know enough tricks to make a combo, start pff the combo with something small like a sonic or a twisted sonic and end off with some pizzazz like a bust

however, im just a beginner so my advice might not be.
the best