Depending on your amount of experience you can skip some of these steps, but if, for example, you get trashed by every player and you can't complete Art of War Early Economy challenge on gold, you should stop bashing with your head against the wall and get that gold. You have in-game training and if you are still incapable to complete it, there is no such guide or BO on YT, that will help you until you learn how to complete the challenge.

Of course you can ask questions, maybe we can even add something crucial to this guide.

If it is your first time in RTS, you should start with playing some campaign just to become familiar with controls. Idk, like two missions. Watch some beginner guides if you want. Play a little bit more campaign and let new stuff settle in your mind a little.

Five main points of focus. These are the golden rules not for AoEIV, not for the franchise, but for the whole genre. You have to master them 100%, no exceptions.

• Always produce Villagers. No matter what situation is, no matter if it is 10 seconds or 1 second, idling Town Center is always a mistake.
  
• Villagers should never be idle. There is an icon with them in bottom left. Use hotkey to select idle Villagers.
  
• You should never get limit locked by the lack of Houses. See limit number go yellow? Slap a House. Production should never stop.
  
• Use hotkeys to recruit units. Mouse clicks are only allowed to do occasional stuff, like upgrades which will come naturally, don't think about that for now
  
• Use Ctrl groups. You can start simply. Ctrl+1 group is your main blob, Ctrl+2 is your cavalry or archers or siege. Ctrl+4 are your main unit production buildings. Barracks, Archery Range, Stables. Get familiar with how to use Ctrl and Shift when selecting units. You don't even AoE4 guides for that, every RTS does that mostly the same way.

Regarding unit selection for Ctrl groups. Double-click or Ctrl+click to select all units/buildings of that type on your screen. Shift is to select/deselect a unit/building without deselecting everything else selected. When you have selected various types of units/buildings, you can see what you have selected in your UI. And there is a small frame which show hotkeys of which subgroup are currently available to you. By default "All" is selected, which provides a usually useless mix of hotkeys of all subgroups. You can press Tab to switch between subgroups to get full access to corresponding hotkeys. This is especially useful with different buildings selected together.

Now on to the next part. In singleplayer there is a tab Art of War. Get silver medal in Early Economy and Basic Combat challenges. For now you are supposed to start every game like you was taught in Early Economy. And you should learn by heart the rock-paper-scissors system from Basic Combat.

Cavalry > Archers > Spearmen > Cavalry.

If you don't know a proper build order yet and/or don't know what counters what and how, these two challenges are an absolute must.

When you feel natural at RTS, knowledge you've gained from those two Art of War challenges should be enough to beat hard AI. With some experience of course. Where do we get that experience?

Now is the time where you can choose your first civilization and start learning it.

The most beginner friendly civilizations are English with their Longbowman build order and French with their Royal Knight build order. This is mostly because they don't have unique macro mechanics which take time to learn even for experienced players and also make it hard to understand how the core of the game works if they are your first faction. You are free to decide, but I would suggest sticking with English first at least for some time until you kinda understand the game on basic level. French can be hard for inexperienced players and somewhat deceptive due to their faster villager production.

There is a lot of common stuff among factions. Though they are still different. Learning the core of the game through one faction is the most comfortable choice imo. You learn unique to your civilization stuff and focus on mastering the core of the game. If you constantly jump from one faction to another (as a beginner/noob) you will not be able to peel off layers of unique civilization mechanics properly in order to concentrate on how the game and everything relatable to every civilization works

There are two paths of further learning:

1. Focus on just playing the game, figuring it out by yourself etc.
2. Jumping straight into build orders.

Let's dive into them a little.

1. There are people who don't want to jump straight into meta and stuff or just want to figure the game by themselves. That's ok. You can skip build orders and go practice on AI and properly gather gaming experience. Constantly produce workers, follow timings from Early Economy challenge, always spend your resources (2k+ of something is unacceptable. Your economy is underdeveloped by the same amount of resources that got stacked up in your bank). You always can build second/third/fourth/fifth production building to produce more units and utilize all your resources. And never forget to build new Villagers.
2. Build order (BO) is a set of instructions and timings of what, when and with which worker do. Objectively the most effective way of economy development for your strategy. These are the same thing as debuts in chess. If you learn a build order and become able to perform it, Hard AI will most likely immediately become a joke to you and you will be able to compete with somewhat average players. If you never forget to build Villagers. You can find build orders on YT. The game just got released, so the amount of BOs is rather small, but it will change soon. Same as platforms with BOs and guides will start appearing and developing. Never forget to build Villagers.

In any RTS there is macro and there is micro. Macro technically means your economy, your grand scheme of things, while micro is related to small manipulations with units. Obviously most of the times micro happens during battles. I would heavily focus on learning macro and everything related to economy before focusing on micro. And on learning how to never forget to build Villagers.

In RTS you learn how to macro until it is in your muscle memory and you can fully focus on micro.

Never forget to build Villagers. At least until you have 80 of them.