Unless you're a chocolate fireguard, grips are as easy as it comes.
Hopefully whoever put the previous ones on didn't use 4 tubes of superglue on the left hand grip like on my bike. Just, carefully, use a sharp blade and make a cut along the length of the grip and they peel off. Clean up the bar and throttle tube, removing as much of the odl glue as possible.
Get youself some hairspray and spray the bar and some inside the grip. Carefully slide them on and wait for the hairspray to set.
Job done.
Hairspray is better than glue. I was sceptical at first but now I have seen the light.