We suggest making a trip around mid-morning. Don’t forget to take a camera with you, since all the symmetrical beauty of Humayun's Tomb makes for killer photographs. You can also lounge or meditate on the surrounding lawns for a while if the great outdoors is your thing. Post that, you can check out the enormous heritage park Sunder Nursery, which is right next to it and has become a picnic hub in recent years.
The location of this picturesque tomb was chosen deliberately for its proximity to the dargah of the Sufi saint Hazrat Nizamuddin Auliya, which is where you should head in the evening (7:45 PM - 8:30 PM) for a peaceful, spiritual experience.
Hungry? Visit the Nizammudin basti where you can devour a Mughlai feast of kebabs, curries, and biryani, which is just five minutes away. If you want to go to a cafe, head to Carnatic Cafe, Cafe Turtle, 360°, and Cirrus 9.