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 learning something new, 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 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 by the skein not the hank. Skeins can be knit from without having to form them into balls. 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 you have successfully completed a few knitting projects.
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.
