How do I get good results with marinaded venison?
Venison is, generally, an extremely lean meat. This means it responds well to two cooking methods: very very fast and very very hot (grilling, perhaps roasting with a lot of basting, or lard the meat first), or very very slow and moist (braising). This is of course dependent on the cut; loin is best grilled, shoulder is best braised (due to the connective tissue), leg is best roasted.

I wouldn't use plain water as a braising liquid. 50/50 water and red wine, or stock and wine, or just stock... cider would be lovely, so would various juices.