Just to list a few to try:
Community College Hero series
Heroes Rise series
Psy High series
The Hero Project series
Love at Elevation
Paranormal Preparatory School
Rent a Vice(a great classic!)
Saga of The North Wind
The Twelve Trials(a personal favorite)
Wise Use of My Time(another personal favorite)
Zombie Exodus(another another personal favorite)
Zombie Exodus Safe Haven(another another another personal favorite lol)

Hope this helps lol