TimeSplitters 2 missions are extremely linear - you simply go from point A to B to C and make sure you watch for any of the optional bonusses along the way. Here are the steps I took to get through these levels.
I also want to put up notes on all of the little challenges and such but some are super-easy and some are quite challenging, so I think putting up a page on every one would be too much, but a page on them all might be too hard to navigate. While I figure this out, here are some random notes on the challenges.