Everybody observes Passover kashrut to their own ability and whatever you choose is a great start.
The 5 forbidden grains (chametz) and are the main things that you should avoid are wheat, barley, oats, rye, and spelt.
Chametz (חמץ, "leavening") refers either to a grain product that is already fermented (e.g. yeast breads, certain types of cake, and most alcoholic beverages) or a substance that can cause fermentation (e.g. yeast or sourdough). The specific definition varies between religious and ethno-cultural traditions. The consumption of chametz and, under the oral law, its possession, are forbidden during Passover in most Jewish traditions.
In Ashkenazic and certain Sephardic applications of Jewish Law, "chametz" does not include baking soda, baking powder or like products. Although these are leavening agents, they leaven by chemical reaction whereas the prohibition against chametz is understood to apply only to fermentation. Thus, bagels, waffles and pancakes made with baking soda and matzo meal are considered permissible, while bagels made with yeast, sourdough pancakes and waffles, and the like, are prohibited. Karaite Jews and many non-Ashkenazic Jewish traditions do not observe a distinction between chemical leavening and leavening by fermentation.
For some extra reading, there is a full product list from the Kashrut Authority that you can look at - http://www.ka.org.au/index.php/Pesach_Products_Directory/