Always start with as few keywords as possible, because each additional keyword constrains the result set, since every item of your term has to match the ones assigned to the picture.
To avoid a disappointing low amount of hits from the beginning, the smartest approach is to provide a common keyword first, have a look at the results and then narrow your search step by step by adding more keywords:
As already mentioned above, all your provided keywords have to match the ones assigned to the photo. Speaking of search engines, it is a conjunction (logical AND).
If you search for pictures of women and the photo also has to include at least one apple, simply type in:
You may also exclude keywords by prefixing a minus sign directly to the unwanted keyword:
While most keywords also exist as plural in our database, we strongly recommend using singular:
When you're searching for women with red hair,
you'll get all photos with women, hair and something with the color red. The results are quite imprecise. To avoid this, try to surround words which belong together with double quotes: