• Use positive, pleasant images. The brain often blocks out unpleasant ones.
• Exaggerate the size of important parts of the image
• Use humour (perhaps linked with point 2)! Funny or peculiar things are easier to remember than normal ones.
• Similarly rude or sexual rhymes are very difficult to forget!
• Symbols (e.g. red traffic lights, pointing fingers, etc.) can be used in mnemonics.
• Vivid, colourful images are easier to remember than drab ones.
• Use all the senses to code information or dress up an image. Remember that your mnemonic can contain sounds, smells, tastes, touch, movements and feelings as well as pictures.
• Bringing three dimensions and movement to an image makes it more vivid. Movement can be used either to maintain the flow of association, or can help to remember actions.
• Locate similar mnemonics in different places with backgrounds of those places. This will help to keep similar images distinct and unconfused.

The important thing is that the mnemonic should clearly relate to the thing being remembered, and that it should be vivid enough to be clearly remembered whenever you think about it.