In the first spoiler thread, I said things were going pretty well for my first game on Monarch.
Well, that went out the window!
The situation in the middle ages was that I had found everybody. I had also decided to go military against the Hittites, and had taken several of their cities, though i had to stop early because they brought in several civs to help them. I went to war with the Hittites a second time and removed them from the home continent. At first it was looking like the offensive was going to stall, but then suddenly the Hittites just fell apart.
After that, I decided I needed to do some catching up on tech, but it was difficult to get the bigggest civs (Ottomans and Iroquois) to trade with me.
At the close of the age of sail, the Ottomans declared war on me, and despite the fact that I was well behind them on tech and most of the Eastern Hemisphere was orange by now, I did pretty well. First I got the Portugese, Koreans and Hittites allied with me. Second, I managed to keep them from ever landing any troops on my territory. Third, I landed a force on their mainland. I sent several cavalry and an army stocked with knights over to Istanbul and began pillaging, getting most of the squares around it pillaged before the Ottoman moved infantry stacks onto the rest. Meanwhile the rest of the troops were punding away at one of their coastal cities, but cannon, cavalry and medieval infantry weren't a great recipe against the infantry garrison, and after awhile I moved the stacks back to the ships so they wouldn't be wiped out by counterattacks. Then I made peace and got some gold out of it. As a bonus, I got to see Mursilis say he was going to go home and shoot himself.
From there it was all downhill...or maybe a better description is a plateau. I kept up the research, but long before the game ended the Iroquois and Ottomans had crossed over into the Modern Era and left me mired in the Industrial Age. Noting that both of them had massive militaries and that the Ottomans would be just shy of a domination victory if they conquered me, I started building up my military with the best units I could--infantry, guerillas and artillery. I couldn't upgrade my navy because I had no oil and no one would sell it to me. The Ottomans built the UN and never called a vote, I presume because they had no idea how the Hittites and I would vote. Eventually, the Iroquois launched their spaceship in 1973.
What did I learn? Something I should already have down: Don't futz around, have a goal going in and work toward it like a fiend, never letting a turn pass when you are saying, "Hmmmmm...What the heck am I doing now?" A backup plan is nice, especially early--"OK, archer rush...aw crap, I'm on an island with the Greeks!--but I needed to work one from the get go and I didn't.