I just went for a cruise couple of months back.
Star cruise usually has a series of activities on board that you can join in. The activities usually start as early as 6am to late at night like 12am. Check out the programme sheet in your cabin.
Personally, I feel that the food at the free buffet is not nice. You should go eat at the restaurants. The chinese or western restaurant has a set meal which is also free, but only you can choose either 1. However if you're still hungry, you can go up to the free buffet to eat since that one don't have any limits.
The set meal menus are usually put outside the restaurant so you can check it out first. I will recommend you to dine at Bella Vista (the western restaurant) for either chinese or western set meal because the restaurant is bigger. more seats.
The cruise ship is pretty big, you can slowly explore each levels and then see which activities to join in. The popular ones will be Bingo. But you'll need to pay for the tickets. Its quite fun..
If not, just walk into the casino, put a bit of money into a slot machine and then you can ask the attendants for free drinks, like coffee, milo, water, honey, etc etc...