Skills are divided into two types:
Military
Economic
Military skills are designed to increase your damage in combat.
Economic skills improve the bonuses you receive when working for other companies and increase the production efficiency of your own companies.
Until level 20, you should focus exclusively on economic skills.
If you're wondering why, it's very simple: before level 20, You won't have enough skill points to make a meaningful contribution in wars, and above all, you won't have the economic strength (money and equipment) to face a period of war. That's why You need to build a strong and stable economy first.

(photo of https://app.warera.io/user/6969696041d32ac9dd035da8)
This is the table you should follow when distributing skill points in the economic branch.
The step number doesn't correspond to your character level. It simply indicates the order in which you should allocate your skill points.
You must follow the table with the skill points available, because as the point allocation increases, the demand for them increases.
Don't spend your leftover skill points on random abilities. If you can't move on to the next step, just save your points until you have enough to unlock the required upgrade. The saved points will be added to the new ones you earn as you level up. (See the example below.)

In this photo, the character's level is 15. Looking at the table, you can see that the level is 16, and to reach 17, you need to assign 1 point to production. To advance in production, I'll need 8 skill points, and right now (looking up), I have 2 left, waiting for the required 8 points to assign the point.
Please note, this doesn't include points for increasing the company limit and employee limit; those are up to you, based on your gameplay preferences.
Considering what's been said so far, the goal is to reach level 20 so you can be included in the battalions and start doing significant damage in wars. Along the way, it's CRITICAL to build economic stability, and to do so, allocating skill points to the right skills is essential.