While there is always some debate about when to communicate & the answer is simple, the sooner the better.
If you delay to long, you may find yourself left out as other players make peace deals or war pacts against you.
Talking with your neighbours can give you a feel for whats going on, whose fighting who etc, also keeping comms up as the game progresses is important, especially if your cooperating with a neighbour or to run a fury farm or arrange a temple swap for instance.

If your mailing a player & they’re not responding, they may be inactive? You can check on this by clicking on his citidel, here it will show the last tick he logged in, but at any rate, you should always regard silence as aggression & prepare for attack.

How you present yourself makes a difference not only now, but in future games, if you come across sounding like a bully, you won't get far... be Firm but Fair & save your serious side for the battlefield.

Some terms you may hear are:
NAP = Non Aggression Pact, an agreement between neighbours to remain at peace.
Fury farm = neighbours build forts & send lesser at each other to “farm” fury for spells.
Temple swap = neighbours with different religions build & swap temples with each other to gain access to more forms.
Forms = These are the creatures that can be summoned by choosing a certain religion.
BB = Black between, each time you cast a BB spell, your forces will be upgraded.
GL = Game long, as in GL NAP.
3 ticker, 5 ticker = 3 tick or 5 tick Nap

Other terms you may hear:
NG = News group.
CoC = Code of Conduct. (see Community section)
Maccing = Playing two accounts in the same game is against the rules, please play only 1 account per game, if your caught, extra ID's will be deleted.
YIM = Yahoo Instant messenger, a common host to secret negotiations ;)