The easiest (maybe only) way to get this trophy is to fight a shielded enemy and not break his shield. That way you can keep punching him indefinitely and not run out of things to hit
I got this on the very first occasion you fight enemies with shields, so there was only 1 to fight and walls either side for me to headbut him into.
You can use you other moves if you want to speed the process up, but just keep hitting him so he can't get an attack in and with a bit of patience, you should have this trophy with no trouble at all
EDIT: I didn't realise this at the time, but there is also a 300 hit combo trophy. This method should work fine indefinitely, so do yourself a favour and keep going to 300 when you do this!