Extra Granted Maneuver, Weapon Focus, and Power Attack or Stone Power.
If you're going for a two-handed weapon, take Power Attack instead of Stone Power, and be a rampaging death machine. If you're going for a shield and a one-handed weapon, take Stone Power to play up your raw toughness to further levels of insanity and be a nigh-unstoppable juggernaught.
Another set of good choices is Exotic Weapon Proficiency (Spiked Chain), Combat Expertise, and Improved Trip. If you want to be cheesy, then a Crusader can be ever so very cheesy with a spiked chain. But in that case, your 6th-level feat ought to be Combat Reflexes, and you better have a good Dexterity (14+ is preferable with CR). It'll probably do you more good than Extra Smite.
Vital Recovery can also be very useful at low to middle levels (and it's at least some small use at upper levels, unlike the Toughness feat). With Extra Granted Maneuver, you'll probably be recovering maneuvers at the end of your 3rd turn in each battle, so you'll get a nice jolt of free healing at that point in most battles (the ones that last more than 3 rounds, anyway). You might substitute this for Stone Power if you're going for the sword-and-shield or hammer-and-shield approach, at least until 6th or 9th level, but at either of those points you should pick up Stone Power anyway.
For a slightly different defensive approach, you might go for Devoted Bulwark, White Raven Defense, and either Martial Study (for another maneuver known of 1st or 2nd level, like Burning Blade, Steel Wind, or Shadow Blade Technique) or Martial Stance (for another stance known of 1st-level, like Iron Guard's Glare or Leading the Charge; you should already know Martial Spirit and either LtC or Bolstering Voice). Then you could qualify for the Faith Unswerving tactical feat upon reaching 6th-level.
If you have Player's Handbook II, then Shield Specialization and Shield Ward could be handy for defense, alongside Stone Power, Power Attack, Extra Granted Maneuver, or Devoted Bulwark.