The 4 most important thing early on are:
1) Complete GW every single day. Since you don't have a big roster yet, get some healers. Jedi Consular is a very good healer for GW because of his quick cooldown. Luminara is also a great healer that you can get with GW currency. Finally, Old Daka is a great character that stuns, heals, and resurrects. She should probably be your first character from cantina currency, but once you have her unlocked feel free to switch to someone else.
2) Obtain some Scoundrels. They're used in the credit heist, which is a biweekly event that awards massive amounts of credits. Once you can complete GW consistently, I would recommend getting some Scoundrels.
3) Get one character to 7*. It really doesn't matter who it is, just get somebody to 7*. If you're a dedicated player, you should be able to find a guild that completes the Heroic Rancor that will accept you, even if you only have one eligible character and can't contribute much.
4) Keep in mind the Emperor and Yoda. The Emperor is unlocked via an event that can only be attempted with a team of five different 5* Rebel characters. To get a sixth and seventh star for the Emperor, you have to have a team of five 6* Rebels and then five 7* Rebels. Unlocking Yoda is done the same way, but using Jedi instead of Rebels. Both the Emperor and Yoda are incredible characters. While unlocking them might not be an immediate priority, anybody that followed my first tip should already have two strong Jedi, Luminara and the Consular. It isn't a bad idea to get Qui-Gon out of the cantina store and farm two more so that you can get Yoda.
