Just to add a few things pre-level 20 (don't know post, yet)...
1. Also, she should use the other abilities like Shout and Anger, etc. Not sure about strategy on which to use first (still learning the tanking aspects within EQ2) but here's a couple of scenarios:
1.a Your group fights a single group designated mob. Taunt/Anger is fine for this encounter.
1.b Your group fights a pack of mobs. Shout would do well here to ensure that all the mobs in the group are only attacking the tank. If you don't have a main assist and one of the mobs stray to another party member, taunt or any other ability should bring it right back.
2. Assault is a nifty (IMO anyway... hehehe) AoE attack to help in keeping group mob hate. But it also affects mobs outside of your engagement. So your wife should be mindful of the battlefield and use this ability to her discretion. Would suck to have an add in a challenging battle (not that I speak from personal experience or anything, oh no!).
3. After AC, she should focus on upgrading hate management skills; Taunt, Shout, Anger, Hold the Line, Intervene, Soldier's Stance etc. Then if funds permit, offensive skills and weapons.
You two can check out the
official fighter forums which should have good strategies from Fighter -> Paladin.
I'm not certain, but if your group can coordinate group HO's, maybe she can get more hate when she completes the HO with Taunt/Shout/Anger/etc. to help with hate management? This I don't know. But it would be nice to get a little extra spike of hate this way.
Other than that and her finding her own timing with her hate keeping routine, it's up to the group to help her with hate management.