Your style of scrapbooking may change, too, as you learn to scrapbook. Buying a lot of stuff before you get started - It can be over whemling to get too many supplies before you even make a page. Get your basic supplies and make a few simple pages, Then start shopping with the project in mind. If you are working on Christmas pages, then buy enough paper and stickers to go with that theme and get the pages done.
Extra supplies can really be a burden as they add up.
Buying a lot of supplies before you have a place to store them - Even as a beginner, you need to have a place to keep your supplies. But an organizer that can grow with you. Leeco Indusctries makes a number of scrapbooking organization tools that are part of a system. Highsmith makes acid free cardboard storage modules that can work as part of your scrapbooking storage.