2. It is very important to develop skills such as Education and Training.
Because when exchanging with other heroes, you transfer as much as 75% of the experience. Why? It's simple: you develop secondary heroes along the MANAGEMENT branch to increase gold and resource gathering, which brings you 20% more gold when picking up resources, as well as a 1+1 bonus for ore and wood. This is a good exchange rate, and most importantly, it reduces the cost of buildings in the city by 20%, increases the army size, and allows you to build 2 buildings in 1 turn. And of course, VIGILANCE is also a good and useful skill!