Use "&" to find images that contain both words:

image & photo

Use "|" to find images that contain either word:

image | photo

Use "-" to find images that contain "image" but not "photo"

image -photo

Use "(" and ")" to group parts of the search

(photo | photograph) image

Use quotes to match a phrase

"the best photo"

All of these may be combined

"the best photo" & (portrait | travel) photographer