When to go
All months of the year are suitable to photograph the Treetop Walk in the Gardens by the Bay.
A visit in the late afternoon (16:00 - 18:00) will allow you to photograph the sun peering through the clouds, although the sky is absolutely brilliant during sunset.
Field tips
Using a wide-angle lens (35mm) gives you an optimum field of vision of the canopies, allowing you to capture the treetop walk from end to end. It also blends the backdrop of the Marina Bay Financial District, which in my opinion makes the photo stand out so much more with its silhouette aesthetic.
Get low! Similarly with the wide-angle lens, it allows you to capture more, but most importantly, gives a different perspective of the location. All too often this place is captured top down through drones or at eye level, so stooping down - be it crouching or lying down - changes the perspective and really brings in the sky and sun auras!
Framing with trees gives a natural composition and leads the viewer's eyes to the center and most aesthetic component of the image: the people! The treetop walkers are the biggest game changer in the photo, and by using the Supertrees as a natural frame, the perspective is enhanced and emphasizes the subjects.