OK, trying to learn a different opening, I dropped back a difficulty level to Noble, took the Carthaginians, and went straight for Bronze Working (very easy because they start with Mining). Hannibal's Charismatic helped with the happiness problem pre-Monarchy. Same building sequence as always, Warrior, Worker, Settler, Stonehenge (while second city makes another Settler).
Someone eventually tossed Buddhism my direction and at about 1300 ad it's now my state religion, running Theocracy (because I'm building an army). I was down to 20% tech for a while, back up to 60% now with multiple Courthouses and Markets, cranking out Knights and getting ready to stomp some Khmer butt.
Thing is, it's a lower diff than I usually play, and I lucked out with no fewer than four gold tiles, two in my capital's FC and two for other cities. With my old strat, on Prince and without the gold, I'd be running 80% tech. So I'm still missing something. I could have clobbered someone earlier but there was room to peacefully expand as far as my economy would allow anyway, so no need.
BTW, a couple of disagreements. I see nothing wrong with using minor cheats like saving/reloading, especially in the early game where one stupid mistake or stroke of bad luck can destroy what could have been a fun game otherwise. I sometimes do the same thing if I have a force about to attack a barb town that I think probably will be capable of taking it but I'm not sure, to see if I want to go ahead and go for it or wait until I get another unit or two down there.
Yes, rapid expansion like the settler rush in the early game is resource intensive and I've never gone into full missionary mode until after I've settled all the cities I can up front. Missionaries are for when you have 6-8 cities already, and you need the extra cash so you can build a good army.
When I say "all the buildings I need," I don't mean every building I could possibly build. I also don't mean buildings I don't have the tech for yet.

Obviously in the early game I don't have factories or universities built.
I disagree that having enough units for deterrence = being ready to go on the warpath. It's not even a question of having a big army built beforehand. You need to have at least two cities, usually three, ready to crank out units non-stop, one or two for attack units and the third for garrison/stack defense. Also, there's the question of being able to keep and administer the conquest once you've got it, unless you're planning to do the scorched earth routine, which I don't usually like to do. With war weariness, periods when defense outweighs offense, and the economic penalty for big empires, the game seems to reward a peace-war rhythm, rather than constant war. For me anyway.
I do agree that using the same strategy every time gets old, and also I know I'm not making the best use of some civs. That's why this thread was kind of interesting to me, in that the OP uses the same strat I do, and I've considered the possibility it won't work on higher DL, at least not for most civs.