The worse that can happen is that the gamemaster will say no. The order of actions in combat is determined by the character's Initiative skill. The highest Initiative skill goes first. During a surprise situation, characters must roll their Initiative in order to act. Rest, Pass, Free Move, Engage, Disengage, and Attack.
Engagement is a critical concept.
A character can only attack an opponent that he is engaged with. Only engaged characters can attack with a melee weapon. The Rest and Free Move options are only available to unengaged characters. The attacker declares his Target, Weapon, Weapon Aspect and Aiming Zone. The Target of a melee attack must be an engaged opponent.