I agree that drinking water is an excellent way to help eliminate fluid retention. Parsley is excellent for helping get rid of excess fluid, as are watercress and dandelion root.
Exercise can also help prevent fluid retention.
believe it or not it's to drink more water. making sure you are drinking lots of water helps to flush your system and keep you from retaining water.
also there foods help
Foods that cause you to release fluid:
celery
onion
parsley
garlic
peppermint
eggplant
cabbage
cranberries
asparagus
corn
cucumber
grapes
watermelon
Some sources say to reduce intake of parsley and celery to avoid water retention. I believe this is based on the fact that they contain a significant amount of natural sodium. Organic, or naturally occuring sodium, may be helpful by keeping table salt in solution, helping to eliminate it.
Hopefully this helps you :)