Just be careful with clary sage. It doesn't work for everyone. I had a lot of prodromal labor with my last one and so would use some clary sage to push it into active labor. Every time it would shut down the contractions I was having. I figured that my body just wasn't ready and so that's why it wasn't working. Then when I was finally in good, productive labor - 6 cm, 90% effaced and bulging bag - my friend rubbed clary sage on my feet to try to speed things along. Well, within half an hour everything shut down. Completely. I mean, I went over 3 hours with not a single contraction. They finally started picking up again, but I had a lot of bleeding and ended up transferring to hospital to just get the job done (I'm sure the clary sage had nothing to do with the bleeding, though).
So, just be wary of the clary sage. There are good reviews on it, but in the research I did there are just as many stories of it having the opposite effect, including my own experience.
Lavender is nice and relaxing, though. I have had some good luck with using peppermint to help with nausea as well, and ginger oil is supposedly good for that, too, although I've not had as much success with it and I can't stand the smell. LOL