Levels, skills, command, Age of Heroes Online

On every odd level you receive one skill point. Skill points are used to get new skills of your hero. All skills have definite demands - to hero's class, to his level, and the set of previously gained skills.
There are three levels of skills - apprentice, specialist and master; they differ sharply in strength and efficiency.
There are passive and active skills - passive ones give constant bonuses and effects, active ones - must be used by hero in battle during his turn. Magic spells are also active skills.
Consider, that the highest possible level in the game - 60th, highest possible in this version - 15th. So take it into account.
Every hero has four characteristics - attack, defense, magic and knowledge. They are improved automatically, on every level, in its own manner for every class. The only way to have an influence on them is to use artifacts.
One point of knowledge gives 10 points of mana to hero.
Specialize in peculiar skills - consider, each of them is much stronger on master level than on apprentice one. It is better to be a specialist in one area than have small skills in all areas.
Skills are divided into groups - attack, defense, speed etc. These groups develop differently for different heroes, but common rules are quite simple - knight is strong in attack and defense, marksman - in shooting and speed, and mage - in magic.
Of course there are some exclusions - elven warriors know some spells, and orcish hunters are good in close combat.
Remember, that it is impossible to be the strongest one - each hero has his advantages and disadvantages. Take it into account when you go into battle.