Well.... monsters have to be learned.
But there are a few tips that always help out. For Jade Barroth, and all Barroths really, always fight their left hand side (your right when facing them), if you are doing close range melee. This is because its tail will ALWAYS swing to his right (your left) after a charge.
Tip 2: Do NOT be afraid of the Barroths... This means, walking/running away from them is surefire death. Walk into his legs and to your right.
Tip 3: Know when to put your weapons away. If you see him back off, just put your weapons away, and get ready to do a run->dive. If you have the camera lock, this will be even easier since you will see when he is rushing back towards you.
Finally, Don't worry about negating snow attacks. If you are standing where Jade Barroth is and eating the snow attacks, you are going to get killed, even if you are not turning into a "snowman". The meager damage you will do while it is shaking will not justify the 20-50% health you will loose during that same time. You are much better off staying away from him during that time, and carrying some "cleanser" to remove snowman effect if you do get hit by a snowball.
Hope that helps, and TKMT's advice is also good if you need more evasion. Don't forget to have fun btw... even if that means ignoring the Jade Barroth for now. Frustration is a game killer.