Closed maps learn you how to boom and learn you more about late game battles. Open maps are almost all about the early game. It is all about putting on the pressure early.
There are multiple strategies possible. Scout rush is just one of them. To just name some other: Drushing, M@A rush, archers, … Just learning the basics for each kind of rush one by one is fine. It looks like you started with scout rush, which is fine.
A good scout rush is executed early. This means you need a good build order to get to feudal quickly, while also have the resources to build the stable and make scouts, while also sustaining villager production. The current meta seems to be a 21 pop scout rush, so you will be in feudal before 10 minutes. Some civs will have a good eco bonus, so they can hit feudal age even more quickly. A civ like Mongols might even go for something like a 17 pop scout rush. I do not recommended such build while learning the ropes. I would advice you to stick to the 21 pop scout rush.
You can find many build order guides on the web. I will give you an example:
Many people think picking off villagers is the many goal of a scout rush. I would advice you to make this as side goal. Your main target is to get as much idle time as possible. Hit and run tactic will lead to micro, so you need to balance the micro of your army with the macro of continuely creating vills. Hotkeys might help you to become better in microing while still being able to create vills.
Like i already said: The main goal is to force idle time for your opponent. This means i would move out pretty early. 3 scouts with no upgrades is already enough to start harrassing your opponent. You dont really need much scouts to harrass the vills.
The number of scouts you made pretty much depends on your follow up. The same is true for the upgrades. It really depends on your preferred strategy and the strategy of your enemy.
- If you go full scouts, you just continu make scouts and do bloodlines at some point. You can also make a blacksmith at some point and also do some blacksmith upgrades. You can even add a second stable to really gets lots of scouts. If it is scouts vs scouts, you probably want to add your own spears too.
- If you go full feudal, you also continu make scouts, but you also want to make an range and add probably archers. This was the meta years ago, but i havent really seen this strategy much in recent years.
- If you go scouts into archers or skirms, then you wont want to make many scouts. I would say that you just make 3-4 scouts at most, before making archers or skirms. You also dont want bloodlines or blacksmith upgrades at all for your scouts. Scout were only a way to get map control. You never planned to go full into cavarly. So it isnt worth it to invest in those blacksmith upgrades.
- If you go scouts into knights, then you also dont want to make many scouts. Your main focus is getting to castle age. You make scouts to just delay the attack of the enemy. So you might want to go for just some scouts, Maybe 5 at most. Just so you have time to get to the castle age before you enemy can move out with their archers. Since you want to go heavily into cavarly in castle age, it might be good to get bloodlines on your way up to castle age, so you can produce knights with bloodlines. Two stable knights with bloodlines and some scouts still alive make bloodlines worthwhile.
How to fight with scouts? It is mostly hit and run. Spears are deadly for your scout, but scouts are much quicker. Just use that advantage. Just run away from the spears and force some idle time. If you are lucky you might kill some villagers in the mean time. At least you will force some idle time. I have played some game in which the enemy had created 8 spears, while i just had 4 scouts running around his based, while just doing some semi FC build into archers. So the enemy wasted a lot of resources. The AI will probably do something like that as well.
If i go for a scout rush, i just go for just 3-4 scouts in most games. Then i switch to another unit. Which unit depends pretty much on the civ i play and the strategy of the enemy. I almost never go full scouts. Only if the enemy also go for mass scouts, i want more scouts. And i would add spears as well. In almost every other case i would just make some scouts.