Motion Tracking footage that moves fast, and in different directions (Difficult problems) (Mac After Effects Cs5)

Hello people of CreativeCow, first off just like to say this website looks great and hope to get to know some people with great information.
I am currently editing a short film for myself, it is a war film and thus involves some effects. I decided to try my hand at blood splatters and being able to motion track items, such as wall hits, blood, posters etc to walls. Here is the problem i have tried to motion track the footage and when applying the track data to the null object problems seem to reveal themselves. I tried places a blood splatter and the blood moves and doesn't look realistic, now i understand this is a common problem, however i feel because my footage moves fast and pans down thus leaving the initial track area that might be the problem?
I have tried many different ways but i cant seem to get the tracking to work, also as am working with the whole film edited without effects, i cut the part i wanted from the main clip yet it never takes the analysis from the cut? I have tried to read up on this but i never seem to find anything that is deals with my issues?
I do apologise if this has been asked before or am ignorant to other material/posts. If anyone could please aid me in anyway it would really be appreciated as i cant seem to get this right.

Thank you very much

Andrew.