Good question, and I still have problems with this, but the one big tip I've gotten on this has been to change things like, 'She looked away, as if fighting the urge to laugh,' to 'She looked away, fighting the urge to laugh.'
So just try to avoid things like 'it seems' (one of my biggest issues), and maybe instead 'it was.' 'It looked like' is another one to avoid. A more direct statement, though potentially a little flatter, can help to erase a passive feel.
~Hope this helped a little! :)
~*~ What is once in a minute, twice in a moment, but never in a thousand years? ~*~