You can make a windbreak look more natuural several ways:

1. Stagger rows as mentioned above;
2. Randomly plant the different types of plants paying attention to their growth rates and eventual sizes.
3. The wind doesn't turn corners well. You can plant the windbreak in groves with gaps between them. As long as the wind can't blow straight through because there are some trees blocking the way in or out of the gap, then it will function.