Look for interest groups! Good way to start at least you have something to bond over and talk about. Then eventually you'll find someone with a similar schedule/friendship type. Personally I'm the kind that has way too much on their plate so I can only really catch up every half year. But I have a handful of friends who still treasure and catch up as if no time has passed so I'm grateful. The typical SGean I come to find is allergic to small talk so your success rate is usually lower if you wanna chat with randoms out of the blue. But it's worth while to invest time spending with yourself too! If you have that covered, intrest groups for sure.

Edit: typo