basically, the garuga has only 2 annoying attacks.. the scream and the windpress. i understand that you're still in high rank so i'd suggest that you go for the armor skill that has high grade earplug so you can evade most of the time. also, if you're familiar with the attack patterns, try to attack the head as much as possible.. most of your attacks will bounce but the head is the weakest part and most vulnerable. it usually does the charge attack abnormally in rage mode without warning so limit your attacks for at least 2 to 3 hits on the head and dont be greedy.. i always failed the quest that way and pisses me off! lol
use flashbangs and shock traps. never use the pitfall. sonic bombs are hard to come by so save them instead. if you have the time to cut off the tail then go for it. a sign to look for is when the monster will "rest" its ears.. it means it has low hp just like a yian kutku would. dont forget to watch out for the poison tail whip and back flip! yeah, this is a mean monster and if compared to a rathian, id avoid this one first.. no element weakness. you can also try sleep bombing the bastard.. goodluck! :D