If you get the feeling that you photographed everything, or lack imagination when stock-working just do the following:

- make a list of your favourite 10 categories

- pick one of the categories randomly and draw/photograph something on that subject

- next day you pick another subject...

..and now a little exercise of creativity... (sometimes its hard to photo something from that special category you just picked):

- open any book and put your finger on the surface of any page at random.... look.. it will be a word you picked.. try to combine that word with the specific cathegory.

Here's an example:

Suppose you have the "business-metaphor" cathegory and you take a book and accidentally place your finger on the word "heart". Then you get the idea of drawing a heart exploding ...