A few tips of the top of my head. (I don’t know the multiplayer meta, I think they should still be useful). These tips are sometimes in conflict with one another. Try to balance them.
Optimize your resources
Short version: Minimize resource waste.
Long version: In order to rule a successful empire you have to manage your resources.
Since a percentage of your stored resources will waste away at the end of your turn if unused, saving up is usually not a good strategy (power is an exception since the stored amount IS its purpose). Especially in the early game, the amount wasted quickly approaches your yield of that resource.
You should therefore as a rule try to spend all your resources every turn. This brings us to the economy tab, where you spend wealth. In the early game, the important resources are knowledge and food, so unless you want to buy a military unit, wealth has no use and you should spend 100% every turn.
Buying tiles is relatively cheap, so having a stockpile of unused food is easy to avoid. Technologies, however, are quite expensive, so the wasted amount quickly becomes significant. Try to plan what technologies you want, and allocate wealth so that you can barely afford one of them next turn. If you decide not to unlock one next turn, don’t allocate any wealth this turn.
Cut off competition
Short version: Greed is good.
Long version: Try to secure large areas for later expansion by expanding aggressively. This involves expanding towards and securing prime city locations before the competition. Building a city in region with lots of unclaimed tiles, will end up paying for itself very quickly due to the flag discount.
Short version: Greed is not THAT good.
Long version: Avoid claiming tiles which can be contested by other empires. If the other claimant gets the tile, the result is just that you have wasted food. If none of you get the tile, it will hurt you both, while the other empires expand unhindered. If you really want the tile, unlock a power technology and/or consider whether the other empire is likely to claim that tile.