For the first play through, you should be able to max out your social stats. Your stats carry over to your next play through which gives you plenty of time to work on confidant levels. Books, DVDs, games and movies can get you points if you choose to spend time with those, before going to the theater make sure you read the cinema aficionado book to increase your point gain from movies. You can also gain points while working the Crossroads Bar and talking to the different patrons, but who you can talk to seems to be random.
Studying at the diner while it’s raining, getting the answers correct in school (you can hit the touch pad to see how others answered for the correct response), ranking up your Star confidant.
Trial by Burger at Big Bang Burger, at captain rank it’s 3 points if you succeed each time, and you get 2-3 points for charm, knowledge and proficiency too. Ranking up your Death confidant. You also get a point in guts if you order coffee at the diner.
Working at the Beef Bowl, batting cage, crafting infiltration tools, ranking up your Hanged confidant.
Working at the flower shop, ranking up your Tower and Hierophant confidant. You can buy the best fertilizer from Shinjuku to feed your plant once a week, this doesn’t take up a time slot and gets you 3 points each time.
Bathhouse, especially when it’s raining or if it’s Monday and Wednesday, ranking up your Death and Sun confidant. Going to the Maid Cafe.