Tangent, but I found wing involved nearly as much work as flanker if not more. Between covering back for kicks/counter-attacking, plus the onus on the blindside wing to make a run everytime, wings should be really sodding busy, and possibly do more running than any other back.

The fitness is crucial. When you're not doing it, you forget how ****ing hard it is to keep running and working when something heavy thuds into you every other minute. Flankers should be the fittest bodies in the team.

Get your rucking technique right. Forget jackaling at first, you'll probably do more good simply driving over the top of rucks. You do that by going low and hard. Practice that. If someone's jackaling your ball, grab hold of them and just fall over to the side. They'll come with you.