I have straight asian hair too

When my hair is damp i smooth in some aero volume mousse into my roots and the ends of my hair and then i section my hair out and blow dry using a large barrel brush. After i'm done blow drying i take sections of my hair and back comb it and spritz some hairspray onto it and when i'm done i run my fingers through my hair so it doesn't look too volumized.

For curly hair without using a curling iron i use heated rollers instead, works a treat and looks so much more natural and easier to use. Or i use the crazy huge thermal rollers in my hair to create big waves and lots of volume. Hope that helps hun!