You can roll saves at the start of your turn instead of at the end of your turn. A successful save against ongoing damage, for example, means that you will not take the ongoing damage that turn.

Adventurer Feat: 

You gain a +1 bonus to saves.

Champion Feat: 

Once during your turn as a free action, you can choose to lose hit points equal to your level to reroll a save.

Epic Feat: 

You gain a +1 bonus to Physical Defense and Mental Defense.