I second what droid said, particularly in regard to saves - some saves stack (see the wiki link earlier in the thread), and I've found that can sometimes really add to your survivability. Play with equipping and unequipping items while looking at your saves on your character sheet to see what will stack and what won't. (For example, I know the trinket from Delera's will stack with the +2 Fort Save on the Gatewarden's Girdle from STK.)
I'd also consider at least one DR item, if you can, or and/or a fortification item (at *least* Light, higher if you can get it). Spell Resistance is a plus if you have trouble increasing your Will saves, or even as a bonus on top of that to help with regular spells tossed at you like Hold Person, Otto's, etc.
Blindness Ward can be your friend, particularly against some monsters like Air Mephits or NPCs that like to blind you (like the end boss of The Graverobber). It's possible to still move and fight if you're blinded, but you're at a huge disadvantage from not being able to see anything besides your UI!
Now and then you might be lucky to run across a Freedom of Movement item; consider slotting one if you're having a tough time with Will saves in quests that spam movement effects.
One of the things I'm having a *lot* of fun with is a Fearsome prefix on my chainmail shirt and the Invis Guard on my Cloak of Night from Mabar: when both of them proc, it's hilarious to see monsters run away in lots of confused directions.
In short, play with the options others have suggested and see what else you can come up with that suits your play style.
