GetButton Problem

Here's a part of code:

 if (Input.GetButton ("Aiming")){
     target.animation.CrossFade ("aiming");
     walkSpeed = 0;}
 
 
 if (Input.GetButton("Aiming")){
       
 if (Input.GetButton("Action")){
      
       target.animation.CrossFade("shoot",0.1);
 }}

What I actually tend to achieve is make it work like so: if Aiming button pressed then aiming animation's played and only after that I can press button Action to perform shooting action(play shooting animation). But on the other hand if Action button pressed first and then I press Aiming button, I don't want shooting action happen and let character stay in idle pose just like no button was pressed. I guess I need somehow block Aiming Button Input when Action button is pressed. Any ideas how to achieve this? Thanks for your feedback :)