Before making a decision check all available talents from four available columns.
You gain one talent point every two character levels. Most of them are passive skills that gives you various bonuses and boosts to character stats. Frequently they improve previously chosen skills, increasing their effect or area of damage.
Talents are divided into four groups: class, offensive, defensive and utility. First group, as name suggests, consists of talent available exclusively for the class you play with. New talents become available as you reach new levels. Other three groups consist of more than dozen talents available for all classes no matter of current character level.
During first phase of the game pick class talents. They are usually matched in a way so that they are best suited for created character. Further in the game you can choose few talents from other groups. When playing a magic class - wizard or druid - most of your choices should focus on class talents. When playing as melee fighters adding few talents from offensive and defensive tree is necessary to create a strong character.