emttim
Contributor
This is basically all you really need to do. Yes, buoyancy helps, improving trim helps, and being in good physical shape helps, but I'm not physically active right now due to lack of time and my buoyancy probably isn't perfect, I keep forgetting to do a weight check and see if I'm weighted correctly or not, but relaxation and breathing technique alone has allowed my SAC to come down from around 1.1 CF/min initially on the first dive after I got OW certified to a range of between 0.29 - 0.40 CF/min where its at right now on dive #61 or whatever I'm at right now.
Just relax, consciously control your breathing (although adjust it as necessary during diving as needed for fine tuning buoyancy of course) and your SAC should drop tremendously over time.
And like others have recommended, I purchased a HP steel 100 tank so I had plenty of air to dive with in the meantime while my SAC wasn't so great. You will not regret purchasing one of these tanks, because even after your SAC improves, it will remain quite useful because you will no longer have to get a fill after every dive. I typically only have to get a fill on my 100 after a second dive using the tank and its great not having to break down my kit after the first dive (hey I'm lazy). Also if you get to this point, you will likely not even think of bottom time anymore because you will be limited by bodily functions and not air. These days, me and my dive buddy end the dive long before we run out of air or NDL...usually one of us has to take a leak, gets cold or gets hungry before we get low on air.
