I too play deity domination almost exclusively. It is, imho, the easiest way to play once you get the hang (AI is abysmal at combat) of it. After you've conquered ~2 civs its almost impossible to lose. But I enjoy the perpetual combat slog and tending to my garden of 40+ cities. Thoughts your guide:
Upgrading vs. hard building units is 100% accurate. Delay archery until you've got at least 3 slingers. I would definitely add/emphasize the importance of the Mercenaries civic & Professional Army card. Of all the possible timing pushes, that one is pretty universal and important to plan for. As you get close to unlocking it you'll want to have gold/strategic stockpiled, your units close to home, and the techs unlocked. Ideally, have a different civic 1 turn from completion, slot the card when you unlock and empty the bank upgrading stuff, then take it off next turn.
The other universal timing pushes is walls. You'll actually see the walls being constructed in-game. If you do, it might be time to start bashing melee into it because if they go up. Your archers and warriors are screwed.
Maybe I'm wrong on this but I rarely if ever build encampments early and thus almost never have the luxury of a GG. Only time I bother is if I can buy tiles and place a cheese encampment in range of a capital. Then take it down slowly solo with a catapult safely tucked in to farm XP. GGs are great, but if you're building encampments and holy sites early, you're foregoing campuses and that is going to hurt.
Chops are big. Tour de Magnus to get the most out of them is great. With the religion strategy section, I would definitely add that farming era score is a big part of what makes religion worth it. Loyalty and eras was a HUGE update to domination play. With a religion, if you convert cities as you're attacking but before conquering (and you're always conquering) you've got an infinite source of era score that guarantees constant golden ages.
Full disclosure I just skimmed the last section that's civ specific. Unless they get their UU early, my domination strategy doesn't change much.
So big things I'd add:
1. Learning combat. Basically if you any units die, (distant scouts aside) you messed up. You got greedy, moved up too quickly, or are in a war so far behind in tech you can't win. If its the first two, I recommend practicing on a slower game speed. Speed makes domination even easier because the AI is brain dead at combat & movement. Slower tech/buildings/eras, means more time to move troops, which humans do better, which is how you win. The AI will move troops up to attack, even when defending, and kindly invite you to slaughter them. Good example: you're chipping away at a city. A new enemy unit moves into view and hits somebody. The AI (to my knowledge) is supposed to mass at least 2-3 units before moving in. So if one pops out of the fog more will follow. You should pull squishies out of range of the city, kill the units, then move back in.
2. Always be war-ing. There is functionally no penalty to being at war for centuries. War weariness is very marginally impactful. As long as you keep a war going with an AI, it is focused on the war and falling behind in econ. You are farming XP, hopefully still doing OK at econ, and gaining pillage yields. The caveat to this is that making peace occasionally for a few turn break can be worth it. If you just took a city, their next one is a long walk, and you're about to unlock an impactful tech upgrade, milk them for a nice peace deal, lick your wounds, then re-position again. Grievances are maybe worth considering early. But after you're ~5th capital every one will hate you either way. If you at any point can ally somebody you don't plan on killing for a while, even if they're charging resources, do it. It'll confuse diplomacy for everybody else because they hate you but like your friend. And delay the inevitable 'everybody left alive hates you' coalition.
3. Loyalty & Ages: Imo this should be its own section. If it needs saying, Golden/Normal/Dark ages determine your city loyalty output. If you end up in a dark age, conquering somebody in a golden age will be nigh impossible. Conversely, if you're golden and a neighbor gets a dark age. They are your next target. Eventually you're snowballed and this doesn't matter. But early it is very important you don't stumble into a dark age if you want to keep war-ing. That said, its not the end of the world. If you're OK at sim city, you can start conquering in the industrial and still win. Just keep an eye on the science leader.
4. Promotions. Ranged eventually gets attack twice. Siege gets move&shoot and 3 range. Melee gets +1 movement and no movement penalties for rivers/water. Light cav gets 1 movement point pillage. Those, imo, are the most impactful. Even if your early wars aren't marginally successful, the more late game units you can get with those are important. Relatedly, when you unlock corps/armies to combine units, obviously don't smash two 4th promo ranged together. Take a zero promo and merge. If you really want to micro, the XP gain buffs you get from barracks/armory/academy are inherited when merging. So when you unlock armies, build/buy a cannon in a city with a stable/armory/academy to combine with your cannon corp. It now gets +25x3% XP gain.
Last thing. The logistics card is my favorite card in the game. +1 movement builders just means less IRL time spent micro-ing them. And it effects your units as you move forward conquering the majority of the time.
Thank you for coming to my ted talk.
