Leveling and Initial Artifact Suggestions
Lots of people have been asking how they should set up their artifact for the expansion. This is the best advice I have. An up to date version of this advice can be found in the FAQ and Resources section of #Ravenholdt: https://discord.gg/4daJYEf
There are still a lot of open TC questions and the answers may shift based on evolving TC understanding and/or further tuning (see http://www.twitlonger.com/show/n_1sp1u8g for more details).
I suggest putting points into two artifacts as a hedge against further changes. Outlaw should be one of those specs since it is highly versatile and currently appears to do the most damage in raiding situations.
For a second spec a strong case can be made for both assassination and subtlety. Assassination tends to better at lower gear levels and has competitive sustained cleave while subtlety tends to be better at higher gear levels and on burst AoE. Both specs can burst well with high regularity. Level outlaw 13 points to get Greed (path: http://www.wowhead.com/artifact-calc/rogue/outlaw/FCpuIsBBwBQeAUIQFCQDQoA0KgNUQBA) and either assassination (path: http://www.wowhead.com/artifact-calc/rogue/assassination/FEsKIrAUMDFIAxSgMUwBFaARWwFPwBA) or subtlety 13 points (path: http://www.wowhead.com/artifact-calc/rogue/subtlety/FB-HIRA1MBNVAzVwM1gDNfATYgFUUBA).
After that hold your artifact points until raids open and/or things settle down and we have a better sense of tuning.