Photoshop and PaintShop Pro are two excellent programs I use. You can get custom graphics, buttons, bars, etc, for your site by making them. Free art is okay, but be careful of copyrights, and never steal graphics off web pages. Animated graphics may look cool, but they can get irritating quickly. Try not to use too many of them.
Photographs always are interesting and helpful additions to a web site.
However, be careful of file size. Because you want to get your point across, choose colors that contrast well. Black is easy to read on white. Black is not easy to read on navy. White is a better choice for text on navy.