Ive tried using feint and trip and with no success. When i feint an enemy, it says successful and nothing happens. When i trip an enemy it appears to work, but my character trips instead. Is it just me or do any of the special commands (other than coup de grace) work?

I've seen Trip used against so I guess it works but I don't know about Feint. Feint isn't that useful so I never worried about it.

Of the other special actions, I know that various forms of Ready actions work fine.

Check your dice rolls when you do it. When you feint, you should drop their AC for your other characters on that round. When you trip, you're probably not making a high enough roll and you get tripped instead.

Feint works, it takes away the opponents dexterity bonus to AC iirc, and is very useful for a rogue with the "Improved Feint" feat.

Improved feint lets you use it as move action which means you can feint and then attack in the same turn.

So a rogue locked in combat can feint, and if successful, follow up with a sneak attack. All the rogues I build use this tactic.

Trip also works and is very useful if you use the right combination of character, attributes and feats. iirc it's a strength vs strength check of some sort, dwarves get a +4 bonus automatically, and you need the "improved trip" feat to avoid provoking an attack of opportunity.

So a high strength dwarf with the feat is the way to go. And if successful the opponent is royally screwed as getting up provokes attacks of opportunity from everybody in range.

edit: now that I think about it, the +4 bonus for the dwarf is only applied to his check to avoid being tripped himself if he fails his trip attempt.