Everyone has to know the basics of the glows...
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Step 1 Open up a new document with a basic shape in it on a new layer;

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Step 2 You can give this shape several layer-styles including 2 different glowes.
Each glow is also different by itself..
If we add a white inner glow the ball looks like it is made out of glass.

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Step 3 When we give it a black inner glow, the style changes automatically. Now it looks more 3d and round.

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Step 4 The same goes for outer glows. If you have a white glow, it looks like it's really glowing.

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Step 5 But when you have a black outer glow, it looks more like a shadow behind it.

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Step 6 Combine both black glows and you will get an even more realistic approach of the orb.

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Step 7 Combine the white and the black glow and you will get a glowing ball...

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Step 8 You can also duplicate the orb and blur it to give it a nice outer glow.
That way, you can make multiple glows..

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Step 9 The sizes variate also ofcourse as you can see in the example below.
You can give really realistic effects with the glows if you wanna go for a realistic approach.
If that's not your goal, then it has tons of other various outcomes.
My advice is just to experiment with the glows ;)
