So any tips to a newbie, or some lightweight reference resources you can share?
Compared to Civ5, you want more cities.
The biggest contributors to your science, gold, culture, faith and production are the Districts. A city can build 1 district, +1 for every 3 population. So as long as a city can reach 4 population fast, and 7 population eventually, its worth building. As in, its worth building any city with at least a few good tiles (it can also work specialist slots on its districts).
Districts themselves have adjacency bonuses: industry from mines, science from mountains, culture from wonders, etc. These are worth planning. The game by default has a planning tool, where you can leave notes on the map and therefore help plan your district layout.
Without mods, districts can't be destroyed or replaced. Put it in the right place.
Compared to Civ5, cities are weaker at first.
You need an army to defend your city. Later you need to build a military district and walls on your frontier cities. In combat, you need blocker units in front of your ranged units, which are very vulnerable. When attacking, you need siege units.
Great generals only buff units of the same era as them, it specifies what era that is on the unit itself. They are very strong. Great people can't die, so you can scout with a great writer and stupid things like that. If captured, it will just teleport to your nearest city.
Compared to Civ5, the policies can be changed.
You want to do some stuff in bursts. For example, place the policy that builders get +2 charges, then produce/buy many builders, than remove that policy to replace it with something else when you are done building workers for the moment. Similarly with producing military units or districts.
I don't know if governors and golden ages are in the default game or expansions, but their use also encourages you to do things in bursts. And similarly to that, the eureka moments/inspirations for researching cultural or scientific institutions also rewards setting things up, like researching archery 2/3 of the way in, and then competing it with your slinger killing a barbarian.
Nature reserves only become possible in the late game, but can only be built where there's nothing else built, no districts, no improvements, and require high appeal on tiles. So that's something you may plan on turn 20 and do on turn 200, for a tourism boost.
tl;dr the game requires much more planning, because important decisions aren't just momentary like clicking a social policy or building a wonder on the same tile as the city, many things require or reward deciding things in advance and setting them up.
The AI isn't good at doing this. Over time you will outcompete it. The AI will be stronger at first, and weaker later, to an even greater degree than it was in previous games.
