New POE player, tell me something you wish you knew when you started playing

Hi guys,

New PoE player here coming from D4. Really enjoying the game so far. Given the depth and complexity of the game, what is one thing you wish you knew when you first started playing PoE?

On a side note, I read that the next season is due in early Dec, am I wasting time by playing this season given its going to roll over in around a month?

Thanks!