Some seasoned knitters insist that all knitters should knit with wool [natural animal fibre]. I DON'T AGREE! I firmly embrace the "KISS" principle--Keep It Simple Sweetie. When the process of learning, I do not like to pile it on. I want to learn the basics and then I want to proceed from there.
Wool requires special care. You must learn to form a ball from a hank; to block your work; and how to launder your wool garment. Knitting is a challenge to learn without piling on these additional lessons.
Synthetic yarn does not require blocking. It is sold in a form that you can begin to knit immediately. Synthetic yarn is also easily laundered--simply machine wash and dry. Knitting with synthetic yarn is knitting without "baggage."
Beyond these considerations are those of price. Wool generally is far more expensive than synthetic yarn. If you are not sure you are a knitter why break the bank on wool?
Still, wool has its allure. There is nothing like knitting with it for pure sensual delight. However, it is a pleasure best left until after you have your first couple of projects completed.
That said, there are many fine synthetic/wool blends that offer the ease of synthetic and the luxury of wool. Look for them in your local yarn shop or on the web.
(Quoted from Yarn Therapy: an introduction to knitting by Leanne Dyck. Exclusively available from the dragonfly gallery on Mayne Island.)