I have been bringing up a warrior. I have 2 ways to apply Battle Shout.

Smartbuff - Check Battle Shout and "in Combat" in both the main options and under "Battle Shout". This way you can hit the smartbuff button or call it via /click command {/click SmartBuff_KeyButton}.

Macro - This is the one I usually use because it's just easier. It's my pull button, so it's easier to just double-tap it at the start of a fight

Code:
/cast [nocombat] Charge; [combat] Battle Shout
/cast Berserker Rage
/startattack