Also the action of a character can negate your action. Say two characters attack the same enemy, if the first one killed it then the second one's action had no effect. It is all chance and the roll of the dice.
Also if the enemy has first inituitive it could change things, say it vanished then niether attacker stand a good chance of hitting it.
It just turned invisible and didn't move then shots into the space where it was last seem might hit, again it is all in the rolls.
so post what you feel your character would do and hope for a good roll.