Strong Hand on Top
To get everyone doing this right, first try and make sure they have hurls that are not too long, as that leaves space at the top of the hurl to put in the weak hand on top (golf swing). Get your players to stand in a circle with their strong hand on the hurl and their weak hand behind their back. Get your players to pull left and right with the one hand on a piece of grass on the ground. That will get them used of having strong hand in dominant position. Then introduce second hand on the hurley and repeat the exercise of swinging on the grass (ready lock and swing). Keep watching to ensure weak hand isnt being put on top. Move onto the tyres then. Usually after three sessions of this, about 80% will have the grip right. The others just need constant reminding but will eventually get it right.
Toe of the hurl out
Right handers turn the toe to the right and left handers turn it to the left. If the players dont mind, I use a marker to put reminders on the bosses of players hurls. I put a correct mark on the proper side, and an X on the wrong side. Every time they pick the ball, they will see an X or a correct mark looking up at them. They know themselves then.
Catching in the wrong hand
This is hard to change, but you have to explain to your players that all the catching is done with their weaker hand. If they start catching with their stronger hand, they will be all over the place with their technique in a few years time.
If a child wont change
Dont get fustrated if a child wont change. There are always a few who dont like to be told. However, if they hear it from two or three different coaches that they are doing it wrong, they will start to take notice. If you have a guest coach or different helper with you, make sure that you tell them in advance about which lads have to tidy up their technique, especially the guy who wont take advice. Some players wont change until they are 14/15 and become exceptional hurlers then.