Oh dear, I just realized that came out all wrong.

Ok, just to recap, subtraction really is important.

Yes it is ... so here's a set of excellent free video tutorials about mixing. Some are directly related to EQ, and now not to abuse it:

http://mrbillstunes.com/tuition/video-tutorials/

Peace,
Andy.

Someone want to dig out the thread explaining why all parametric EQs should sound the same?

Start by cutting frequencies below 50Hz except for sounds that really need it like bass or drum kicks.

Anything that goes on a whole mix to add 'shine' is almost necessarily going to make something else sound 'harsh'. Ozone is the closest Ive seen to a 'magic' bullet' and it tends to sound overcooked imo. Its all in the mixing.
Imo, the biggest part of adding 'shine', or anything else, is figuring out what it is that will 'shine' in that particular mix. Like, what is it that the ear will pick up on that will tell it 'Shiny!'.
You generally arent working a bass to work on shine. You arent working a hat for muddiness, etc.
That said, for me it is about isolation I guess. With panning and reverb I give those key elements more room. Say I want the hats to pop out and be cystal clear. Well I might check out the snare and see if there are any higher freqs in it that can get chopped. I might do just slightly less reverb on the hats so they sit closer...

The two biggest EQ lessons, imo:
-Think of EQ cuts as 'edits' and EQ boosts as 'FX'. Boosts are adding something to the sound besides just amplitude.
-Use strong hi/low shelf EQs liberally.

Oh and all EQs are the same.

This. Secret Weapon.

look at this:

http://www.youtube.com/watch?v=mvHH6nsNmG8


this is "girl Panic", by Duran Duran; i think this is the most useful example i could do of what i mean by "Shine"; here, no harshness, just clarity and sheen.

About my above question: what is the exact function of compressing only the highest frequencies in a multiband compressor? what does this action do? it limits them or makes them louder? i really don catch this point

If you compress something, then it softens. If you want to limit them with a compressor, you'd have to set the ratio to infinity.

But you can make them even louder when you compress them and then add more makup-gain (than input gain). Then it's less dynamic and louder, a special kind of maximizing.

What you mean with "clarity" seems to be the strict separation of frequency bands. This can be achieved (assumed you have a tidy arrangement) with (subtractive) eq and filters.

The production on that Duran Duran track is sublime

Less is more when mastering.

The only tips I have, still learning myself :

Dynamics and equalization are not independent. Changing one will affect the other. A compressor can be used to rebalance frequencies and an EQ can be used to rebalance dynamics. If your ears can tune into this then anything is fair game, IMO. In fact any effect will by definition change dynamics and equalization, and keeping the ears open to these consequences is essential. On exciters: they're all different, it's more of a category for things that don't fit elsewhere or are interesting combinations of other effects.

By far the most important things for good mixing are done in preparation. Start with good sounds and be organized enough to revise decisions and jump between a few different spots in a mix at any time.

+1! No magic plugin can fix a bad mix.

Might I suggest pebbles around your usb cables?