I think of the font as part of the "art" of it. If it reflects the mood of the picture. Sometimes its good to vary the size for a result you would even think of. Or use one font as a background for another. Also play with the spacing - between letters, between lines everywhere! Fonts are my favorite part of making a layout- they can make or break it (besides the picture of course!) Also, a silly thing I do is to step back from the computer a couple of feet and if I can read the title still.. its good. It's gotta be readable! Some fonts are best left for single words if they are too complicated.
-Doris