How to keep my hair straight?

i have kind of a scene hairstyle with lots of short choppy layers and medium length hair. My hair is a pain to straighten and doesn't stay that way even though i dont have many natural waves or no curls. Any suggestions to keep my hair straight i have a chi straightener and i use hairspray ( not to much) and dont wanna use a lot of things inn my hair (like gels). Advice??