What follows will probably become part of my final post on this game. I played through the ancient age several times before I finally figured out how to handle this game effectively. This describes my latest (and it looks like I'll win) attempt at this game.
Since I knew wheat lie a few turns south, having already played it, I moved more settler and worker crew south and settled near the wheat. I built some warriors and reserached pottery at full tilt. I basically tried to send my warriors out in teams of 2 or more. This way if a barbarian killed one of them and got redlined in the procces I could then kill it. Also, and more importantly, if I spotted an encampment, that way if one warrior failed in its first attack, the second warrior (with one notable exception) would disperse it. I had my settler factory going after a while. My second town lay south along the river. Most of my towns built warriors for quite some time. Occasionally I would have them build a few workers.
Once I knew pottery I beelined for philosophy, pretty much at full tilt, going for the literature slingshot. My second town on the river used a granary as a prebuild for the Great Library, while a mere handful of workers mined around that second town. After I had mined all the squares I could I merged in workers and took that second town up to size 10 (I couldn't take it 12 since I had so many forests nearby). When I got philosophy and then literature immediately after I set my science rate to 0. I built the Great Library, and then built workers out of that second town so that I could drop my luxury rate. Moving along the mountains a good bit and trying to keep an eye on as much territory as possible I didn't have too many problems with barbarians for a while. I built two curraghs at some point who contacted all the other tribes.
Shortly after I finished the Great Library some of the barbs (I guess I played a little carelessly in spots) got a little too close to my towns and I saw that some would sack my towns. Of course, I couldn't really buy tech or luxuries. I still had a despotic government, so I couldn't buy units or improvements. Consequenlty, most of the money I used to build embassies and establish RoPs with everyone. At some point I still had some left over after all the embassies and RoPs. So... I found a banker (usually the French). By this I mean that for the lump sums of gold I had I exchanged gpt with say the French. E.G. I may have traded 400 gold to the French for 19 gpt. This way I wouldn't lose too much when the barbs sacked my towns, and I'd get that money back eventually.
Soon enough afterwards the ancient ages ended, and the barbarian hordes appeared on the map. I had planned partially for this, by creating a "settler corridor" down through the jungle river. By this I mean I parked some warriors along the river so that the "fog of war" got busted and no new encampments could emerge along the river (I also did this in the western mountains). This allowed me to keep putting up new towns... even during the barbarian early medieval rush. So, I managed to secure both sources of iron... and settled *almost* the whole island. The English ended up planting a town in the northern tundra and a northeastern town. The Spanish had a northeastern town, a south eastern town, and one in the northern tundra.
At some point... since I left some of my towns empty so that my warriors could go barbarian hunting/create a settler corridor, the English found an undefended town and razed it. The war didn't last long and didn't cause any real problems (thankfully). When theology came in through the Great Library, I started to research on printing press... thinking I might successfully keep up on tech. Then I realized this simply wouldn't work, and so I did what Great Library players often do. One turn before learning Education from it, I gifted it away. At first I thought I might gift it away to the English, but I decided on the Spanish since they had more cities on my continent. It turned out as the correct choice.
During this time I tried to keep a few fleets of dromons near/next to Spanish galleys. Some of them just disappeared. One of them ran up to the pole, and since I didn't have Navigation yet, they got away. I kept RoPs signed with the AIs throughout the game. After my RoP expired with the Spanish 5-10 turns after I gave them the Great Library, I decided I wanted more techs than I would get immediately. So, I signed another RoP with the Spanish. Then I waited... and waited... for my RoP with them to expire. On the next turn I made demands with the Spanish for technology and when they didn't budge, I kept on demanding until they got Furious. Then I told them to leave my land and (predicably) they declared war. A turn or two later, I took back the Great Library city. It had six resistors. Fortunately, it didn't flip back, and I sent out some medieval infantry to the south to get rid of the Spanish.
From the second taking of the Great Library I learned the rest of the medieval techs except, for some strange reason Music Theory and I think Magnetism (even though two other tribes had it). I also didn't get Theory of Gravity, since no one knew it yet. I set my research up to full tilt, even at some 100+ gpt loss for Theory of Gravity. I started a prebuild (maybe a little earlier) for Newton's University. A turn or two later one of my dromons got attacked by a Spanish caravel... and won... triggering my Golden Age (or "slingshot number three... 1. Great Library 2. retaking the Great Library 3. Golden Age) basically how I wanted it. A turn or two later some tribes learned Theory of Gravity, which I immediately bought. I got my free tech and sold it all around for gpt and military alliances against the Spanish and started research in earnest. I have finished yet... but it looks good.