Usually buying guides aren’t really my thing, but to quickly grasp such a huge game like SWTOR, I didn’t want to spend that much time figuring things out in the game. So I bought a guide from KillerGuides and from their online presence, they have been in this guide industry for quite some time.
I bought their Swtor Imperial Operative guide featuring the beginning parts of the Imperial Agent guide and then breaking off at level 10 to focus mainly on the advanced class or the ever might Operative. From cover to cover, the guide sets out with an introduction and basic knowledge of the SWTOR advanced class and some general strategies. It gets interesting after the intro as the guide features a whole set of different sections on how to play up your character. They feature skills & builds, questing strategies (my favorite part), weapons and items to be used and how to earn SWTOR credits on the fly. If saving time is your strategy to play the game, I would recommend this guide from their site. They even have a SWTOR bundle package deal.