There are some things I learned about just a little to late. Figure I would post what I learned, then everyone could add to it. Heres what I learned, and what I believe every new player should know;
1. Before level 15 you can reset your stats and talents as much as you want. Take that time to learn the many ways the class is played, and if its the right class for you.
2. Anything can be got with time and effort. It will take a LONG time (and im not joking here either, it will take a LONG time) but if you dont want to pay any money to get something from the cash shop, there is a currency exchanger at your factions auction house.
3. There is no "perfect" build. While there are basics of every build, you should always use the best build that fits you and your playstyle.