Etiquette for using 3.X feats in PF?

[Talakeal]

So I am going to be playing my first game of PF tonight. What is the etiquette regarding using options for your character that were published in a third edition book? Specifically feats and prestige classes?

If something has been updated I assume the old version is off the table. But how do you know when? For example, are the fighter feats in PHB 2 still viable or have they been superseded by the new fighter class features that do mostly the same thing? How about the fighter feats in Complete Arcane, which are now just better versions of the feats in core PF?

What about stuff with no clear analogue between the two?

[Blackhawk748]

Id say ask your DM, thats really all there is just go up to them and say

"What are your rules on using 3.5 material?"

and they will usually respond with something like

"Depends on what it is" honestly there may be something in PF that is similar that you havent heard of

[Giddonihah]

Many 3.5 feats are stronger than similar Pathfinder feats. So I'd assume that you are not allowed to use 3.5 feats unless otherwise said by the GM.