Like usual, early game you want to be prioritizing Resistances > Health > Move Speed, upgrading to higher armor bases as you progress.
Added and Increased affixes are top priority for Helm, Body, and Belt. While resists can be solved with affixes applied via forge to any other piece of gear.
Since you'll be using to level through the campaign, I recommend two s or s with . Once you can get both with that affix at T5 plus any resists you can afford to add, these rings should last you all the way to transitioning to .
, , and are also good stopgaps while levelling for obvious reasons.
Once you transition to , the real game begins. The first thing you want to do is reach 100% block chance. You achieve this by using a high block chance shield such as , with T5+ , and getting T5 on both Rings and Gloves. is also a requirement on your shield since it's the only piece of gear that can get it, so make sure that's in your loot filter. Another bump to block chance and health on block can be , but only as a stopgap before transitioning to . You also want a on your shield for high-end content.
Scaling damage is pretty straightforward. + or on a will be your main source of scaling, and the wand itself will reduce 's cost to 0, allowing for infinite channeling. A good amulet will really help boost up the damage, and can remain even if you want to transition do a DoT variant of the build. should be prioritized on all accessories. Two s are recommended.
Getting on your Wand will keep you safe until you can cap out your crit avoidance.
Speaking of which, after you cap resists, work towards adding (at least 30% total) on at least one piece of gear - most likely Boots. the rest should be covered by a high-rolled from empowered Reign of Dragons.
Get Health on all gear that you can afford to without compromising resists. If possible, your Body, Helm, and Belt should have both Added and Increased suffixes. You want around
Resists are straightforward; get to at least 100% on all resists. The shield suffix will assist with this until you can cover everything with other gear since the suffixes you really want are and .
There are also some of double-resist implicit pieces such as that are great choices.
Poison resist is one of the toughest things to solve for on any Sentinel, however the can help you cheat it up to the cap of 75%, and is also a fairly high block-chance base.