Get yourself a "guide" book or two and a few good quality essential oils (try starting with no more than 3 or 4). Once you learn to use those few oils - learn their uses, correspondences, safety information and methods of use - then move on to a few more.
Some of the more popular essential oils to consider starting with are:
- Tea Tree
- Sweet Orange
As for books, there are tons out there... But some of the better ones are:
- The Complete Book Of Essential Oils & Aromatherapy
- The Essential Oils Book
- The Essential Oils Handbook
My last tip is to keep a journal or recipe book. A simple note book will work. I started keeping one when I first started. It works almost like a "quick guide" book. Each page is topped with a type of EO and then I write down all I can about it. It's Scientific name, alternative names, what it's good for, safety information and the best ways to use it (some oils are best used for aromatherapy but aren't great if used topically, and so on), plus any other little tid-bits I find. I also have a notebook (well, a 3-ring binder) where I keep recipes and "how to" information. Most of the recipes I've posted here on the blog I included in there, along with my own two cents about them - tweaks or additions. The point is that my brain, like yours I suspect, simply won't hold all this information perfectly, so having somewhere to keep it all is very useful.
However you choose to get started... Enjoy your new found love of oils! I know I do!