How to make a Proper Icon?

I was wondering, How do people make those Icons that have Transparent Backgrounds? I used to make all my Icons with the Background already in them, since all the backgrounds usually appeared white.
But I would like that background to be transparent, so I can make Icons like the ones that BlackOps has, as well as the Original game.
Can anyone help me?
I use Photoshop with the Nividia DDS Plugin.|||Icons falls under Texturing so I'm booting this thread.
Thread Moved.
Also make sure you read the Useful Info Sticky.
Mike|||I did check the Use info sticky. The topic that covers icons is kinda dead. The link that has the script files is broken, Plus theres no tutorial that covers the Nividia DDS Plugin.|||What I've used for creating icons is paint.net and while I haven't tried making actual clear icons before, I have had to make clear backgrounds in the various layers of my icons to be sure everything meshed fine... and to do that I merely erased the background. |||To make the transparent background icons you just need to create a mask for the unit, basic black-and-white where full black is completely transparent and save that to the icon file's alpha channel, then it gets exported to the dds alpha by the dds plugin. You should be able to simply use the magic wand tool or similar to select the shape of your unit, make that full white, else full black and then use some effect to create a glow from white to black around it (you see how all unit icons in game have a white glow around them?). Or you can usually get an alpha render of your unit from the 3D soft and use that for the mask.