Some warnings as to what's ahead:
1) This is a war game. Not a sim city style game. So many people attack out of random (even if you've done nothing to them) for any number of reasons. Some as silly as things like: "Well my dog had cats recently and my Uncle, well she kinda upset me and told me I had to do 10 jumping jacks to make $20 so I'ma just attack/Kill you" <-- Something silly and completely "out there" like that can happen very easily.
2) This game is a 24 hours 7 day a week 365 day a year game. It stops for no one. Even if you are not logged in, you can still be attacked. Even though this is a US Server, there are people from all around the world in this game/in this world.
3) Politics are very useful in this game (called diplomacy), this is something that you should try learning to be very good at quickly.
4) There are a lot of jerks out there. Lot of people who don't show
ANY respect to others, curse out a lot/ use profanity a lot. Try to stay level headed with these types of people. You can't please everyone and some people are just plain jerks.
5) People will lie to you. Unless there is a good established relationship with a certain player, it is always best to check all sources possible to get the facts straight before acting on an event. "Check yourself before you wreck yourself".
6) Being a leader can be very stressful and can bring the stress to affect your life outside of the game and even affect your mood throughout the day. Try your best to just reassure yourself it's just a game and that people who are jerks, liars, backstabbers, etc, probably aren't anything far from that in real life or have a sense of "unwanted-ness and/or worthlessness" in real life. This can be their escape and how they play (if like jerks) could be them taking out their poor manner of handling life events on a game. As I am a believer, I pray for those people.
7) Always ask questions and those you do lead, be a leader. When you're wrong, admit it. When you're right, DON'T boast and be prideful. The players that join you are NOT their for you to glorify you. YOU are there to glorify THEM and to lead them. Encourage your people, set realistic goals. Each world lasts roughly 1.5-2 years. This world isn't even 1 month old yet (I think) so think in the long run as well. The Grepolis wiki pages are your best friends, start educating yourself. People will not want to follow someone who doesn't have a clue (to become a successful alliance), or is a jerk and so on.
Above all, think of how you would want someone to lead you and how they would speak/act to you and aspire to be the same "ideal" leader. If someone makes a mistake (within reason) don't flip out on them. No one is perfect.
Those 7 should start you off right along with what all else was posted to you for a bit.
Good luck!