When choosing a 'field', you have to take into consideration who is going to be playing there. If you and all your wiffle ball buddies are right handed batters, then it doesn't matter if there's a tree in right field because it won't mess up your game too often. Also, if your 12 years old, you'll want to be farther from the home run fence than a bunch of 8 year-olds. Also take into consideration landmarks. It's a lot harder to tell the difference between a double and a triple in an open field than on a street with trees groping along it because you have trees as landmarks in the street scene, and only judgment in the open field scene. It's a lot harder to tell the difference between a dong and a triple with out a fence there. Also, you want to be on level ground, not a hill or some slopey little area. If you don't have space in your yard, play in the street. If your neighbors whine about you playing in the street and hitting balls near their houses, tell them its a plastic ball that can't do damage at all, if they still whine, either slap them and keep playing or go to a park to play. Also, add some crazy ground rules to the field. The best one I have is when my sister's little pool is out for summer (its always right there in left field) and someone hits a ball into it, its an automatic dinger. Also, if a ball gets stuck in a bush in foul territory and the pitcher pulls it out of the bush and the ball hasn't hit the ground yet, it counts as an out. Think of your own little quirks for your field, the more the merrier, unless you have so many that its not even real wiffle ball anymore.