Best advice to avoid fucking character builds:
Put at least 70% of your attribute points into physique.
Don’t go over a 50/32 split investment in your two classes
Mastery bars. This comes from thousands hours of experience and other GD veterans will agree.
Once you’re more experienced feel free to go past these guidelines but if you follow them you can’t ruin your character.
You don’t need to tell a PoE veteran about maxxing resists.
PoE had a skill that gave you +3 to max fire, lightning and cold resists. Because it was so overpowered, it got nerfed. Three times!
Quite the contrary, when coming from PoE, one of the first reactions is: how on earth am I going to max all these out? And then you discover that there’s no augmentation game, you always pick whatever gives you the higher resist 
Lol, yes, that was literally my first reaction upon seeing the resist list. Regardless, while keeping an eye on it, I found Normal perfectly doable without stretching gear for resists.
Anyway, thanks for the useful responses everyone! I shuffled some things around, now sitting at ~5.5k health, bit better resists, and have Blast Shield maxed out. Started into Behemoth, will spec for CoF+Vuln+Witchblade after I finish that and get Brimstone (AoE still lackluster atm, so will be rushing that in tree).
@adoomgod, those sound like good tips, but Im afraid I’ll have to ignore them for now. Dumped too much into Cunning already, but will likely spec the remainder for Physique. Already maxed Occultist to 50, and need the same for Demo to unlock Brimstone. Regardless, Im not too worried about bricking the character. On the contrary, Im playing with the full expectation of spending some 50-100 hours to come out with a subpar character, but lessons learned to start over with 
Actually, put stats so you will be able to wear all gear you need in endgame. But physique requirement is usually by far the highest. And if you class dont have very good scaling from Cunnng or Spirit (which is the case for 95% builds), physique is the more benefitial stat.
If you dumped too much into cunning, you’ll be unable to wear some heavy armour pieces.
Glad to see you like the game that much! I would say for your particular build doing 50/50 is fine since you will actually be using skills at that point in both masteries (possession & brimstone). Also since you already pumped cunning a lot you could use the extra physique to make up the difference. Sounds like you have a lot more characters in your future :).
What do you mean there is no augmentation game?
I mean, you don’t get to pick augments to use. You ALWAYS need those with the biggest resists. You can’t have a decent level of resists across the board if you don’t make exclusive use of defensive augments.
And even then you’re left lacking in the more exotic department of disruption, petrify, slow, trap or freeze resists.