OK, major YUCK with the lizard images! I don't have an image, rather a feeling. And I don't wait for the urge to sneak up and catch me by surprise I actively summon the image of drinking and then summon my negative feeling. I am trying to get it to the point where the "feeling" is instinctive when I think of drinking.
The feeling I summon to counteract cravings is the feeling of retching, which I did all day the day I decided to get sober. So far it's working well, I can almost make myself physically ill when I summon this memory.
As some people know I am at my parents, where there is tons of alcohol in open containers, I have been taking the occasional sniff of it and each time I do, I feel like gagging. I am thinking it is doing a good job of cementing this instinct:-)