Some short AW points:
1) For government, you want Monarchy. Switching to Communism can be beneficial later on.
2) If you are not used to Monarchy, remember that you have MP. Whenever you move units out of a city it may riot! I still sometimes have trouble with remembering this. Also remember you can fix unhappiness with units.
3) Place towns at distance 3 apart. This is so one town can help defend another in a single turn. You can even switch MP's across the whole civ allowing you to subtract one unit in one city and add it in another one without affecting the ones inbetween.
4) Keep research high most of the time. Money is not as useful and you have to research everything yourself. Do not do 50 turn Min or you will be behind.
5) The GLib is a very powerful wonder in AW since you can't do "2-fers" and have to self research everything. It allows for building up a cash reserve for upgrading units or to save for when you restart research.
6) (Opinion) With fewer opponents, it is better to attack; with more it is better to defend.
a) If you can damage or kill one civ before the next one starts sending large numbers of units, it is a big advantage.
b) However, if 3 or more are sending noticable numbers of units, it is better to hunker down and defend. Try to get very favorable kill ratios.
7) To get good kill ratios...
a) Avoid attacks that leave a unit that can be attacked next turn. Horses are very important because they can attack and retreat. Otherwise it is often better to leave the last unit alive.
b) Build artillery type units. You want to attack units with 1 or 2 hp instead of 3 or4. Catapults are much more important units than normal games.
c) Armies can be used to attack to avoid losing units.
d) Have defenders to cover attackers; defend in mountains; Remember that walls can be very useful in towns. (sometimes the best odds are from defending).
8) Techs you want to get:
a) Bronzeworking - Get this early to defend yourself.
b) Warrior Code - This is needed too or you can't deal with defensive enemy units pillaging your lands.
c) Ironworking and Wheel - These are useful for finding resources. A swords attack of 3 handles spears much better than archers. Horses can attack and retreat.
d) Masonry - Walls are very useful for a defensive game. (With the Greeks defense 3 UU, walls are especially useful. Your best odds will be defending behind walls. In a town on a hill with walls, a fortified Phalanx will defend more often even against cavalry).
e) Mathematics - Catapults allow you to attack injured units instead of healthy ones.
f) Literature - for the GLib
g) Monarchy - Obvious
h) Currency - You have lots of units so markets are very important.
i) Construction - Get cities to size 7 increases unit support.
i) Map Making - Sending suicide galleys across the seas to meet civs that can't get to you, but can lower your research costs is very nice.
j) Code of Laws - for courthouses.
9) Unit support is pretty important. It is even possible to have too many units and find you can't research well. Having more cities (the distance 3 provides this), and getting them to size 7 helps this.
10) Armies
a) In general, avoid building defense 1 armies. They will be attacked by swords, knights, longbows, etc. If you do build one, make sure it is defended.
b) Pillaging the enemy is very powerful. Knights and Cavalry with their faster speed can really hurt your kill ratio. Pillage the horses, iron and saltpeter, and the AI will build easy to kill longbows. In C3C pillaging does not cost a move, you can pillage quickly. Even early spear/phallanx armies whose only purpose is to pillage is worthwhile (worth more than a archer IMO).
c) Armies heal in enemy territory (do not need Battlefield Medicine). This is very useful in that you can attack a city, heal, attack, heal. No need to leave.
d) Armies that lose too many HP will be attacked by every avail unit. If an army is redlined, then defend it or run away. Under 8 hp is bad. However, a cavalry and crusader will attack a defense 2 army with more hp than that.
e) Two armies together can defend each other and are very strong. If you only attack when both armies have 8 or more hp, then if one is red-lined, the other has 8+ hp can defend it. Only if you lose 8+ hp in one battle is your army killed.
11) In C3C, the AI will land more than 1 unit from a boat near undefended cities. Keep all back line coastal cities defended. I would keep 1 or 2 defenders in each, and have a offensive unit for every few cities as well.
12) I think continents is the best for an initial game. Pangea has too many enemies and is harder, and archipelligo just doesn't seem suited to AW.
13) Something that I disovered fairly recently is that if a civ completely owns an island, they will tend to attack pillaging units including armies that used to be safe. (They also build more boats and bombers if it is late in the game - build air defense if this happens).
14) The AI will give top priority to bombarding armies (both with boats and planes - they don't use artillery well).
15) Rails are awesome in AW. Once your defenders can reach any place in your lands, the number of defenders that you need is much less. This can free up lots of units to use for attack and defense in the enemy territory. I find the invasion of well defended enemy continent occurs shortly after getting rails in my AW game (defenders especially are freed up allowing one to hold cities).
I am sure there are things about AW that I am forgetting. But these are what I can think of at the moment. Hope it is useful.