Many mnemonics rely on making visual associations in your mind. The way you create these visualizations will have a lot to do with how well you will remember the information.
The items that you are associating together should be visualized as interacting in some way. If you are trying to associate a stapler with a dog, it is not going to do you much good to picture a dog standing next to a stapler. A much better association would be to have the dog eating the stapler, or picture a dog with a stapler mouth. Not only does this interaction make the image more interesting, but by grouping both objects into one association, you are effectively chunking the material.