From The LNR Book of Knowledge

Spy is the profession for those who don't necessarily want to be on the front lines in combat, but want to pick off crucial targets and apply some nasty little tricks before vanishing in a cloud of smoke. The main weapon of the Spy is the ability to cloak and remain cloaked indefinitely; with their recent expertise publish, this ability has only become more central to the working Spy's methodology.

Spy is NOT for people who enjoy randomly pressing buttons, or for those who have to be on the front lines of every battle, blasting at the enemy with the most damaging weapons and attacks that they have. Spies' action costs are particularly high, even with Medic buffs, and can easily drain the Action bar in three specials. With that said, however, talented and knowledgeable Spies are the masters of battlefield tactics, singling out targets from the middle of a group and working to get said target out on their own and unsupported. There are a number of actions that can be performed while cloaked to gain a target's attention, including the use of fireworks, Instant Travel Vehicles, vehicles, and flamethrowers.

Current trends in Spy lead to one of four templates: the melee assassin, the ranged sniper, the spyhunter, or the jack-of-all-trades.

Melee spies focus on the Razor Slash and supporting lines, high "Camo" rating, and the combination of Smoke Bomb and Venemous Ploy. Melee spies have higher DPS, but a more difficult time closing to their effective range without a Camo rating in the 300s.

Ranged spies focus on the use of rifles, Arachne's Web, and damage-over-time effects. High Camo rating is less necessary to the ranged Spy, since they generally operate beyond the radius of passive detection and far enough out that active detection maneuvers don't overly inconvenience them. Ranged spies have lower DPS than melee operatives, but have the luxury of sitting back to decide.

Spyhunters focus on two fields: high Camo rating, and high Detect Camo. A Camo rating in the 300s is almost required for a spyhunter template, since their primary role is to detect and neutralize other spies.

The jack-of-all-trades Spy dabbles in each of the three above fields, but doesn't necessarily gear his Expertise template toward any particular "flavor." However, this lack of specialization tends to put the "dabbler" Spy in the role of support operative in PvP, focusing on targets that have already been injured, are battling with NPCs, or are otherwise distracted.

As the saying in the Spy forums goes, Spy is the "thinking man's profession," particularly with the specialties in expertise available. Spies and Bounty Hunters have a great deal in common, as each profession requires planned-out tactics beforehand, as well as a great deal of stalking and patience for the right opportunity to come along.

More information on the Spy profession can be found on the SOE Spy forum, linked here: [1]