Another great way to get prepared is to use the Pink Kit, which goes into perenial massage in more detail. It describes "internal massage" because you focus on the muscles that make up that perenial area inside the pelvis, rather than just the skin on the outside (which is what I presume other people mean when they talk about perenial massage).
I haven't started this yet (they recommend the last 8 weeks is the best time) but I have worded my husband up that his help may be required.

In terms of oil - for the outside of the perenium area, almond kernel oil has been recommended to me a lot. Although obviously you don't use any oil for internal massage.