We were on the Jewel twice. We started going to TSAR's dining room for breakfast every morning. Service was quick and so much nicer than the buffet.
If you want to take part in the murder mystery dinner, line up early on the sign up day.
Check your daily newsletter - there is often a "happy hour" when drinks are 2 for 1.
Sign up for the "casinos at sea" program. Doesn't cost anything, but there are daily chances to spin the wheel to win prizes, including a free cruise.
There are often snacks in the casino late in the evening.