Can anyone suggest any tips to get a lower SAC?
Don't know if this was mentioned already, but learn to diaphragm breath.
The exercise: Lay on your back. Place a 3 to 5 pound dive weight on your chest, centered between the nipples. Practice breathing without letting the weight move up or down. Make that a memory reflex and use this breathing technique while you are diving. It should lower your SAC noticeably unless you were already doing this to begin with. SAC reductions of around 25% are common.
PS - Another good option is to take some freediving classes. A big chunk of the class will be about learning to breath efficiently. You need to learn a lot about breathing before you learn how to not breath.
PPS - Invoke the "Dive Reflex" before you go scuba diving. It will release PH buffers into your bloodstream that will relax your body toward the acidity of CO2. That acidity will tend to make you breath more heavily, the buffers will suppress that. You will learn about this in a freediving course.