When my older daughter was finally potty trained, she had a bad habit of forgetting to wash her hands.  I got tired of constantly telling her so to make it fun, I got the soap dispenser that makes it light, foamy and airy since she loved how it felt.  To add to that, I also got the fruitiest smelling soap because she LOVES smelling pretty and I can smell it on her hands so I knew she had washed them.  Also to keep costs down, I've kept the same soap dispenser and buy the huge $1.00 bottle of bubble bath that comes in either Watermelon or whatever fruity smell is available.  I like the brand Landers which is sold at a lot of Shaws supermarkets.  This trick has worked and she never forgets to wash her hands.