The tools you use depend entirely on the shot you have and the effect you want to achieve. You may need to use tracking, motion stabilizing, camera tracing, or mask tracking. It all depends on the shot and what you are trying to do.
For example: Video Copilot's tutorial for sub_surface_skin uses tracking.
Without a well worded detailed explanation of exactly what you are trying to do or some sample footage it's hard to point you in the right direction. if you are new to AE then this is probably going to require several hours of homework to prepare for the project and learn where all the switches are. There is no push the button apply digital plastic surgery switch in AE or any other compositing app.
Give us more detail and we can point you to some possible solutions.
Update: Photoshop has a liquify feature where it detects facial features, and tinkers with them. I am curious if you could do that with After Effects with video.
No, not that simply. It would require a lot of additional skills and a bunch of hand work. Tracking, not mask tracking but motion tracking or corner pin tracking.
Did you ever pull off this effect? How did it go? Which method did you use? Let us know if you still need help.