Hi Peeps,
In response to several PM's I've had, regarding how to get started, here's a few clues on what to look for and how to go about it.
Gear
First of all, you need some gear. You can start with as little as a $50 snorkeling set from K-Mart as it is basically snorkeling. However, If you're serious about trying it out, you'll do better with some more freedive specific gear.
Fins : A decent set of plastic bladed freedive fins is ideal as you can trash them pretty good and they handle the abuse. Long fins are a must if you want to get to any reasonable depth. Something like Cressi Gara's, Picasso Black Teams etc. ~ $180-$220 Try the footpockets for comfort and allow for wearing about a 2mm neoprene sock for warmth and comfort.
Mask : A decent low volume mask which allows good visibility is idea. Buy the one that fits your face best. On a clean shaven face, put the mask on without the strap and draw in a light bit of air and see if the mask stays on. Most are silicone nowadays and are really comfy. The last thing you want is a leaky mask. ~$90-$110. I use a Cressi Matrix which is wicked for me.
Dive suit : A decent freedive suit will set you back around $400 but you can get basic ones for around $250. A good freedive suit will be less restrictive and warmer. You'll need gloves, booties and a hood as about 25% of body head is lost through your head. No need to go camo. For summer around Perth a 3mm will do nicely, for winter a 5mm, for up north in summer a 2mm top only with boardies will be fine, in winter a 3mm long john and top. The more you spend, the better the suit so buy what you can afford.
Weights: Buy a rubber belt, not nylon as the rubber will handle the compression of your body at depth and stop the weights from sliding around. You'll need between 9 and 15 lbs depending on your body weight and wetsuit thickness. You can buy clip on weights at a pound each but this is a little extravagant to begin with. The basic 3lb RULE weights are good to start with.
Snorkel : A good simple "J" snorkel is the best, avoid purge valves and other fancy stuff, they can be leaky and are not necessary. ~$24-$30
Guns: Most favoured guns are Edge, Picasso, Rob Allen, etc etc any rail gun will do the job. Look to buy around a 1.3-1.4 for Bluewater hunting or 1.0-1.2 for shallow water and reef hunting. The more distant your target, the longer the gun needs to be.
To begin spearing, join a club, either Undersea club or Bluewater Freedivers of WA in Perth, or google your local clubs if in another state. It will serve you well to attend a meeting and find out what everyone else is using in your location and ask about gear from the locals, they'll fill you in on location specific requirements depending upon species and diving environment ie sandy bottom, rock reef, coral, rocks and wash, headlands, drop offs or open water.
Types of Diving: There are two types of Diving : Rock hopping or Boat diving
Rock hopping is diving in off the rocks and usually requires a float/flag on a line to your gun. There is almost no where you can do this in Perth Metro area, so don't even think about it.
Boat dives: Most club members will have boats which makes it easy for newbies to get a ride as everyone likes to have bums on seats to ease costs of a day out. Boat dives can be anywhere from 50m off a cliff drop off, to 75km off shore at a shelf or Shoal in the middle of no where.
Don't think you need to have a boat to get great fish or have extraordinary skills. My first open water dive saw me shoot a 17kg Spanish Mackeral with a 1.0m gun just 2km off shore and I shot it in about 15 metres of water but only 6-7 metres from the surface. Many good fish are landed close to shore from Rock hopping. When rockhopping, keep your fish on your float, not your belt in case you meet "company"
I hope this helps as a guide, but I recommend you join a club and learn good practices right from the start rather than learning dodgy stuff and then having to learn the right way again anyway.
Most important: Do NOT Hyperventilate (Rapid deep breathing) to clear CO2 from your system before diving. You are not filling your system with oxygen, you are purging CO2 from your system. CO2 is the gas that triggers the need to breathe. If you expel all the CO2, you will feel like you don't need to breathe when your body is running dangerously low on oxygen, and can suddenly blackout which can be fatal at depth.
Be careful, and

enjoy the awesome sport of freediving!
KH