Depends partly on the polyu you are using. Not all poly is real good stuff. Some of it stays a bit on the soft side for ever and nothing much will enhance it.
However if you have a good poly surface, that's hard dry (minimum 3 days, preferably 1 week) and it's smooth without anything in the surface (dust etc) or other imperfections, then you can use the EEE directly over the finish and it will improve it.
Continual rubbing or mechanical buffing will bring up a higher shine. However if you already have a full gloss you need to ask yourself what it is you hope to achieve by trying to add more gloss. It's a bit hard to make full gloss a fuller gloss. What you should get will be the same or slightly better gloss but an amazing feel that you wouldn't have had before.
For a brighter/higher shine:
You must rub the EEE continually until the desired effect is achieved. It is a cut and polish, not a wax finish, so leaving it to dry and buffing it off won't do anything to bring up a higher shine. You really need to work it till the shine has reached it's peak then remove all residue immediately and buff with a clean soft cloth to remove any waxy haze left on the surface.
If your surface is not perfect to begin with then you will need to lightly sand with 600, 800 & 1200 grit as per silentC's info above, you can go even higher to 1500 if you wish. Then use the EEE.
Like I said it's a cut and polish. It's not some magical remover of imperfections.
To cut the wet look and give a glow:
Again if the surface isn't perfect, do the sanding thing. Then apply the EEE with a soft cloth and wipe it off immediately. You can if you wish, leave it to dry then wipe off with a clean soft cloth. This will give a full gloss finish a glow rather than the plastic wet look. It will cut the shine slightly but should give the surface of the timber an almost sensual silky feel.
If done on a coffee table for instance, you should get a slightly dull look to the finish when standing over it. However when sitting down or viewed from a distance you should see reflected in it, everything on the room.
The quickest and by far the easiest way to use EEE, is to buff it with a Swansdown Mop. This will save you a lot of elbow grease and lots and lots of work. With a mop, you can do in a few minutes, what would take an hour or more rubbing by hand.
A good finish with EEE isn't rocket science, but it certainly is bloody hard work, :sweat: especially when done by hand.
Hope this is of some help.
Cheers - Neil :)