the first time i played it, i basically ignored all the cases and just ran about exploring the randomness of the game, rescuing survivors and buildng my level up. By the time I finished I was level 32 or something, I got ending F i think, then I just restarted the game but got to keep all my stats. So the game was much easier becuase of my level and because I knew where to go and how the games dynamics worked, time wise etc.. I just completed it properly doing all the cases and am now doing overtime mode. At first it was frustrating but now i think its one of the best games ive played for a while.
In regards carlito, just go get the mini chainsaw from adam the clown and run up and hit carlito about 3/4 times. all the bosses are easy with the mini chanisaw, it feels like cheating.