Although your class (or more correctly, classes) makes the biggest splash when maxing your saves, there's a lot you can do with other options to get those saving throws up there.
FEATS -- Let's start with Iron Will, Lightning Reflexes, and Great Fortitude. Each adds +2 to a class of saving throws. For a true save monster, these are at the top of your feat shopping list.
RACE -- Let's rule humans out right away. The extra feat gives a +2 on a class of saves, taking one of the feats above. But you'll get all three of those by level 6 anyway as another class, so what's the rush? In the end, a 6+ level halfling or dwarf, for example, gets all three feats and ALSO has a racial bonus. Half-orcs are even worse than humans -- no bonuses, no extra feat.
Half-elves and elves are also less than optimal. The +2 vs enchantments is not as good as the dwarf's +2 vs spells and poison, or the halfling's +1 vs everything. The elvish +2 Dex -2 Con gives a +1 on Refx saves but -1 on fort saves. Bleck.
Gnomes are a little more interesting. +2 Con gives a net +1 on fort saves. +2 vs illusions is nice. But in the end, not the best choice out there.
Halflings are an excellent choice. +2 Dex gives a net +1 on reflex saves. +1 on all saves is a hearty morsel, and the stackable +2 more vs fear is gravy. Certainly a viable option.
But the dwarf is a save monster's dream. +2 Con gives a +1 on fort saves. +2 vs spells and poisons covers 75 percent of the saves in a game. The only downside is that if you want to be a paladin using divine grace, the -2 Chr is a net -1 on all saves. So for paladins, go the halfling route, aspiring save monsters.
ITEMS -- You won't be able to afford everything you want, so here are some thoughts on the bargains and rip-offs.
Start with the best bargain -- mundane generic antitoxin. For 50 gold, you get +5 on Fort saves vs poison for an hour! +5! If you know you are going to face poison, quoff it before the encounter for medium-duration help ... and even if the poison is a surprise, drink it after the battle to help on those secondary saves! Truly a must-have item. And on the topic of mundane gear, a Cold Weather Outfit offers a +5 bonus on arctic enrironmental saves. For a mere 8 gp, why not put a parka in your bag of holding?
Let's look at the magic items you might like, oh save monster, in order, with best bargains on the top:
- Cloak of Resistance -- Pro: +1 to +5 resistance bonus. Con: Uses cloak slot. Cost: 1,000-25,000 gp, and a bargain at each price.
- Belt of Dwarvenkind -- For the non-dwarf save monster, this is the best! You get all the bennies of being a dwarf (+2 Con, +2 vs spells and poisons, more), but unlike being a dwarf, your Chr penalty is only to skill checks interacting with others. That is, it does not hurt your Divine Grace or Chr-based spell casting. Con: Don't bother if you are a dwarf. Cost: 14,900 and totally worth it.
- Cloak of Charisma -- Pro: +2 to +6 bonus to Chr; adds +1 to +3 on saves if you have Divine Grace. Really useful only if you also cast Chr-based spells. Con: Uses cloak slot. Cost: 4,000-36,000 gp.
- Pale Green Prism Ioun Stone -- Pro: Gives a +1 competence bonus on saves and more. Con: A little pricey, but worth it. Cost: 30,000 gp.
- Stone of Good Luck (Luckstone) -- Pro: +1 luck bonus. Con: A little pricey. Get it if you have cash to burn or are also a skill monkey. Cost: 20,000 gp.
- Rod of Splendor -- Pro: Gives a +4 Chr boost and uses no slot. That's a +2 on saves if you are a paladin and you want to wear a Cloak of Resistance. Con: Kinda pricey -- although by the tables in the back of the DMG, it would cost 32,000 to make a slotless +4 Chr booster, and this gives nice duds and a weekly feast, to boot. Cost: 25,000 gp.
- Ring of Evasion -- Pro: Taking no damage if you make your reflex save is truly sweet. Con: Redundant if you have it as a class ability, pricey. Cost: 25,000 gp.
- Candle of Invocation -- Pro: +2 morale bonus on all saves. Con: gets used up, really pays off only if you are a cleric. Cost: 8,400 gp for four hours.
- Robe of the Archmagi -- Pro: +4 resistance bonus. Does not use up cloak slot. Gives other wizardly bonuses. Con: Cloak of Resistance gives much better return on your investment. Really only worth it if you use a Cloak of Charisma and can't get a resistance bonus to saves any other way. Cost: 75,000 gp.
- Robe of Stars -- Pro: +1 luck bonus on saves. Con: Overpriced for the save bonus; you're really paying for astral travel here. Get a luckstone instead. Cost: 58,000 gp.
- Cloak of Arachnida -- Pro: +2 luck bonus on saves vs spider poison? Yeah, that'll be real useful all the time. Con: Uses cloak slot. I say, buy a Cloak of Resistance instead. Cost: 14,000 gp.
THE COMPLETE PACKAGE -- So take a halfling paladin with the three save feats. Equip him with a +5 Cloak of Resistance, a Rod of Splendor, a Belt of Dwarvenkind, and a Luckstone. You should be able to afford that by 14th-15th level, and it will give you a total rough equivalent bonus of +1.5 for race, +2 for feats, +5 for the cloak, +2 for the belt, +2 for the rod, and +1 for the stone ... +13.5 on top of your base saves plus ability score mods. Not too shabby.
This is part of an extended series on Survivability in Dungeons and Dragons.