Itachi,
I know people say various things about cardio before lifting weights to "warm up" but I don't like to do it. That's why your first set of each exercise is a bit light, that'll count as your warmup. It's not a rule, just my preference after doing some homework on how pre-workout cardio and stretching can actually increase your chances of being injured.
40 reps broken up into how many sets? You do the chest, triceps(the back of the arm) and biceps every time you go to the gym? 60 sit-ups and 40 bicycle crunches seem like a waste of time too. since you're at a gym, you can do lots of diff ab exercises; even weighted ones, which will be far more beneficial than just doing a lot, like you're doing now. Check out
this website for ab exercises, and aim for the usual 3 sets of 8-12.