Bleu I would recommend looking at the major traits and finding some passive ability that you would like to have. At that point focus on that line to get that ability. If you are a low level, you wont be able to go past 10 points in any one line. After hitting 10 and getting your first major trait, move to another line and get 10 in that depending on what 10 point passive you want.
When you can afford the higher level books, you can look at the 15 and 20 point abilities and go from there. It is super cheap to respec at low level so play around with it a bit.
If you love shortbow, start in Skirmishing. If you like the pet start in BM for Masters Bond.
If you love a certain weapon type, look at a trees 20 point abilities, and youll find cooldown reduction abilities for specific weapons, thats a good way to know where to start when just starting to learn about how the traits work.