Things To Do
Activity: Gardens by the Bay
Plan for half a day. This may also be a good option for a rainy day as it's mostly indoors.
Activity: Singapore Zoo
The Singapore Zoo is Sera's favorite zoo in the whole wide world! The next-door Night Safari is pretty rad too.
Activity: Haji Lane
A hip, cool street with cute cafes. Also check out Arab street.
Food: Amoy Street Food Centre
Sample Singapore's famous hawker fare at this dizzying array of old school Singaporean delights, Michelin Bib Gourmand winners (i.e. delicious food at affordable prices), and modernized takes on traditional Southeast Asian dishes. It's probably best to go on a weekday - since the food centre is located in the central business district, many stalls are closed on the weekends.
Food: General
Singaporeans take their food extremely seriously - ask local friend for recommendations! Ben's favs: Chicken Rice; Chai Tow Kuay (fried carrot cake); Roti Prata; Salted Egg w/ (insert any meat, shrimp, fish skin, or veg); Laksa; Nasi Lemak Sera's favs: Yong Tau Foo; Popiah; Barley Drink; Local Coffee (Kopi) and Tea (Teh); Bengawan Solo; HarriAnns (any "kueh" really) Other famous dishes: Chili Crab; Char Kuey Teow (fried flat noodle)
Getting Around
Trains are probably your best bet, but the bus network is pretty good too. Cabs or the Grab (that's Southeast Asia's Uber) app are also a decently-priced option, especially if you're melting in the heat.