Roman provincial, sometimes called Greek Imperial, coins provide a different and fascinating view of the coinage within the Roman Empire. Over 500 cities issued coins under the rule and authority of the Romans, making this a field where even a beginning collector can amass a variety of coinage ranging from common bronzes of the larger cities and Roman colonies to the rarer coins produced by obscure and faraway cities.
For those interested in learning more about Roman Provincial coinage, I recommend reading, Roman Provincial Coins: An Introduction to the Greek Imperials, by Kevin Butcher. It is an excellent introduction to Roman provincial coins.
I also recommend you visit the Doug Smith's Ancient Greek & Roman Coins, An Educational Site on Roman Coins, Greek Coins and other Ancient Coins, http://dougsmith.ancients.info. Truly one of the best ancient coin sites on the Internet. Doug's articles provide additional information on the subject of Imperial and Provincial coins that all collectors can learn from.
One major difference between Roman Imperial and Provincial coins is that, with the exception of the Roman provincial colonies, most provincial coins are in Greek. For those used to reading the Latin legends of imperial coins, translating the Greek legends can be challenging. Once you learn the basics of the language, you will find it similiar in many respects to Latin.