You start out earning 1 XP (experience point) for every point in your word. The level bar at bottom of screen shows you how many points you need to get to the next level.

Hats and Hats and holds increase XP by the bonus percentage listed on that item. For example…if you are wearing a hat with XP +15% and a hold with XP + 9% then you add those together and receive 25% more experience for every word. Note: You get the XP bonus only for the gear you are wearing.

Energy doubles your XP points for every word. It also doubles the gear. Combining gear and boost will soon more than triple the XP you earn each turn!