Learn how to “ride parallel” with your friends who have hectic schedules or families of their own.
When you miss your friends or are in the mood to be social, then schedule a lunch, outing or event with them on your phone.
Call a friend during your long commute, when you will have time to catch up.
If you want to get to know a friendly acquaintance better, ask them out--just like you would for a romantic date. Suggest a specific thing to do together--it can be as simple as lunch or a movie.