I'm in the process of laying down a 6 mil plastic vapor barrier in my crawl space to assist in mositure control. I used this method at my previous residence and it worked quite well. In my case, the soil in the crawl space is damp but there is never any standing water. Relative to laying down the plastic barrier, I plan on covering the entire ground surface except for a small area near the crawl space door which should allow some of the moisture trapped below ther barier to escape to the outside. I've also installed automatic foundation vents that open and close with changes in temperature and leave the crawl space door partially open except in very inclimate weather with a screen over the opening to keep out unwanted intruders.
My question for the group is if there anything else I should be considering such as foundation ventilators to improve air circulation. I would appreciate your thoughts on this subject.