Hah, I just studied this a while ago with James Bardeen, so I would say he is the best resource for learning this! Since you probably don't have access to the physical Bardeen, you can check out:
Physical Review D, Vol 22 no 8 (1980) "Gauge-invariant cosmological perturbations"
Physical Review D, Vol 40 no 6 (1989) "Designing density fluctuation spectra in inflation"
There is also a set of lecture notes I have sitting on my desk by him that claim they are "to be published in Particle Physics and Cosmology" which are dated 1988, so presumably they were published within the next year or so.
If you can find them, the talks are probably the easier of the three, and the first PrD article is the second easiest. The third paper is very nice, but more technically difficult.
This post imported from StackExchange Physics at 2014-04-01 16:38 (UCT), posted by SE-user Mr X