30% of the time sounds alright.
Her potions will be colored differently to correspond with the effect that potion will cause. Black is great fall speed, blue shrinks them, pink puts a flower on their head, and purple sends a small path of dark flames along the ground which will actually put the character on fire for a short period of time while doing damage per second.
If the potion isn't a special one, then the bottle will just shatter against anything it hits and will do modest damage (think Mario's fireball) on impact. Ashley can throw potions like Snake can throw his grenades. The soft throw, medium throw, and hard throw.