Alot of it is plugins. Alien Eye candy can give you the glass, metal, and beveled effect. But there are other ways of getting the beveled effect.
These 3 are created using alien eye candy:
For a bevel effect.
Go to your color options for the paint bucket:
Make one a dark color and the other a light color.
Then go to your pain bucket, click it and select the graient tool:
Create a box with the marquee tool:
Your pointer will be a little plus icon. Go to the bottom of the box, click and drag it to the top.
In my picture, dragging from top to bottom makes the dark color on the dop and the light color on the bottom. So basically the background color box will be on the top. Dragging from bottom to top will be reveresed.
Thats your bevel effect.
To make things look like buttons.
Make a box on one layer. Make a new layer and change opacity to 30%:
Change your paint color to white.
Now, on the top of the image draw a line across the top, maybe using marquee and paint inside of it with paint bucket, make a white line. Do the same on the left. Now on the bottom and rght side do black.
So it should look like this.
Now, you can keep doing this bevel effect for each pixel. Just keep going to the center and making the black lighter and the white darker. This will give you a deeper bevel effect.
The way i did my gradient gives it somewhat of an inset effect. Reversing it would give you an outset effect.
Once you get to know how to use the tools you can look at other people work and get an idea of how they did it.
You can find alot by searching for photoshop tricks. SOme sites give alot of detail and how to work with tools.