I've just finish my very best Diplo game ever.
I believe I'm learning.
Map setup:
.Emperor
.Standard - Pangea - 60% water
.Wet - Warm - 5 billion
Civ: Greeks
Finish:
700 AD
I could make it #4 but I lose by score for the another 700 AD one.
The final screenshot:
Highlights:
.SGL for Pyramids, I'm not quite sure but I believe it was with Currency.
.Ottomans gave me a really hard time attacking me for no reason at all with tons of
warriors at the very beginning (around 2000BC), but they
didn't attack the Hoplites, still they kept destroying my improvements. I didn't even have strenght to attack so I
wait till the war is gone. Then they went for peace and gave me 2 of their cities

.Nonsense.
.AA to MA -
Chivalry as free tech. Not a very good start, but that's ok. I didn't upgrade the Ottomans so they would still be on AA.
.Ripped Ottomans for expansion since they were still on AA. I had no Iron then I went with
Longbowmen 
. Really nice those guys.
.In this war I triggered GA since they finally attacked a Hoplite. It was in the
2/3 of MA. The research was already in 4 turns so I wasted this bonus, but I could build important things a way faster so it was ok. I've left them alone for tech farming purposes with only their capital.
.Expanded till 35 cities since it was the minimum to get Palace 1000 shields like
Spoonwood pointed.
.MA to IA -
Eletricity as free tech. Very nice one. With sci specs and my ring around Cope's my research was 4 turns even without the GA.
.No war in the IA, just workers finishing the job to get
luxuries since the AI doesn't care to make a single road to connect to other civ. I've lost some turns in the beginning of MA since I couldn't get 100% sicence because of this.
.It took me some time to railroad because I had no
Coal, when I got Coal from Russians I had no
Iron. In an island far away I could found a city and finally have it.
.Prebuilt the Palace and made myself sure it would finish in the exact moment I've got Fission.
.IA to MDT - Nothing really important, just usual business to get Fission. Changed Palace to UN and this is it, got elected at the same turn I've reached MDT.
I know I've written a lot now but that's the whole point of the topic, right?
Maybe someone is experiencing problems in Diplo games and I believe there is lots of good tips here.
Besided I was trying so hard to get a nice finish with Sumerians and I've got with... the Greeks! Actually I believe it fits better my gameplay since in Monarch I had my best experience with them also (although I wasn't aware of 99% of the things I've learnt here).
This is it for now.