Easiest place to get dynomight is at the very start of the jeep chapter, on the right shortly after going through the first tunnel three guys run out right next to a barrel. Took me about 5 mins to get the 5x dynomight trophy.
The combo ones can be registered in the opening chapter, not sure what you could be doing wrong, just keep trying.
The sneak attack trophy can be easily obtained in the fortress chapter, complete the platforming section then the first enemy you see in the chapter will have his back to you. Kill him then let his mates kill you and repeat, hopefully if you're like me you only needed a couple more stealth kills for the trophy anyway, took about 2 mins to do.
The ledge trophies are best obtained in the chapter after the SECOND jet-ski chapter. When you start, jump into the water and go around the waterwheel, climb up onto the side of the bridge, there'll be three dudes to your right, just pick em off and reload that chapter. Takes about 5 mins.
The combo ones can be registered in the opening chapter, not sure what you could be doing wrong, just keep trying.
The sneak attack trophy can be easily obtained in the fortress chapter, complete the platforming section then the first enemy you see in the chapter will have his back to you. Kill him then let his mates kill you and repeat, hopefully if you're like me you only needed a couple more stealth kills for the trophy anyway, took about 2 mins to do.
The ledge trophies are best obtained in the chapter after the SECOND jet-ski chapter. When you start, jump into the water and go around the waterwheel, climb up onto the side of the bridge, there'll be three dudes to your right, just pick em off and reload that chapter. Takes about 5 mins.