Trying to make armor set bonuses

Here's the code (blocks)

when global trigger: player deals critical hit

if get item from armor slot 0 of event target entity = iron helmet

add potion strength with level 1 for 20 ticks ambient false particles true to event target entity

if get item from armor slot 1 of event target entitiy = iron chestplate

etc

i dunno how to post images on here so help with that too would be cool