How do you handle advancement and character development?

Stars Reach uses a skill tree system.

Each tree has its own type of experience points. As you use a tool associated with a given skill tree, you will earn that sort of experience.
You can then spend that experience to obtain new skills in that tree. Skills unlock abilities, crafting recipes, and so on.

To use a given ability, you will need a tool equipped capable of using the ability.
No skill trees are off limits, regardless of your choices.

You can learn all the skills in the game, but you will only be able to have so many of them active at once.