It is very hard to know what to buy in the beginning. I suggest this items: a nice cutter that is big enough for 12 by 12. Some Patterned Paper s (but not to many, as you tastes may change). Also decide if you want 12 by 12 (which I suggest) or a smaller album. Card stock is also very important to have at first. Make sure you buy the "right" card stock for your pictures and Patterned Paper s, so you don't let it go to waste. Buy some cheap embellishments that don't require kits, like brads and buttons. Things I would stay away from are: deco scissors, too many cutesy stickers, and brightly colored card stock.
One extremely important tip is: Make sure you buy Patterned Paper you that you will use! It is easy to get caught up the the colors and patterns, but if its not practical, you won't use it!