I hate wasting time (and precious air) descending slowly to my dive depth. Fortunately, the only real limitation when descending is how fast you can equalize. Here are five steps for reaching the bottom quickly, and safely.
Be properly weighted
Do a proper weight check to make sure you can actually sink, but don't overweight yourself.
Cross your legs
I learned this from a divemaster during my open water certification. Take one of your fins and cross it behind the other ankle. This keeps your legs from flailing around and slowing your descent.
Take a breath and let all the air out of your BCD
If properly weighted, this should allow you to sink until your eyes are level with the water.
Pinch your nose
With a free hand, pinch your noise in preparation to equalize as often as necessary during descent. You may look like a newbie, but keeping your hand on your nose lets you reach depth quickly.
Release your breath
Breathe out slowly for as long as you can. You should steadily descend as you release your breath. Your descent will slow down when you take in more air, so let it out for as long as you reasonably can. By the time you must take another breath, you should be deep enough where wetsuit compression and other factors allow a continual descent.
Of course, keep an eye on your depth gauge and anything you may plummet into. Be ready to put air into your BCD as you approach your desired depth.