HuntAway has it...

When processing the deer (butchering it yourself is the only way you know what you really have) remove all the fat, silver-skin and other connective tissues (there will be a large pile of bad meat as your butchering it)...

In the morning before cooking it, place the frozen meat in a large Tupperware container and add water and a large amount of salt for at least two hours...this will remove the "blood", a connective tissue that carries a strong taste and odor...similar to techniques for processing Kosher meats (must be drained of blood, etc)...

Drain off the water/blood and replace with whatever marinade you prefer...I find a nice cheap Italian dressing from Walmart works well...

I have had people who profess that they would never eat deer come back for second and third helpings...