Just one simple comment, try not to have different color of lighting in the same photo coz it make the white balance shift quite easily and u won't get consistent WB through out the photo ..

Check out shin chan's work, he practice consistent WB through out one set of photo.

Others like exposure, composition and flash, i think u really need to practice a bit more ...

u dun need to use the flash direct to the model, if possible put it slightly away and trigger it wireless from your camera. That would create more nature and less harsh light.