When to go
Best season
January, February, November, December
Best time
Sunrise, Morning
In the winter months, you'll have the best chance of capturing Lustgarten covered in snow.
Berlin tends to have late sunrises in the winter, so you can still get a glimpse of the amazing morning light when you come right after opening times.
Visiting early also helps you avoid busy times, like I did when I took this picture on a winter morning. Having a few people in your shot at the park won't make too much of a difference, but it looks best when the park is barren and covered in a fresh snowfall.
Field tips
By using a wide-angle lens, you'll be able to more easily frame the statues and cross in the foreground and cityscape in the distance.
Make sure the sky is clear so you can see the extensive skyline of Berlin. It's even better to visit on a clear day after it's snowed the day before because it'll create a nice contrast between the warm light and cold, stark-white snow.
To create a sense of symmetry, I aligned the statues and cross of the church with the fountain in the middle of the Lustgarten, which you'll be overlooking when you look west.