Getting a Good Start in SWGoH: Part 1 -- Starter Factions

Important: regardless of the faction you go, you will need a handful of scoundrels for credit heists -- Boba Fett is all but required for this and is farmable from the Cantina store and a couple hard nodes. Lando and Stormtrooper Han also help with this.

1) Phoenix
This is the de facto starter team. They have great synergy and you get access to them early: Hera and Ezra from the first two Cantina zones, Chopper from Cantina store, Zeb from GW at level 40, and Kanan from arena. They are rebels and get EP later on, and two are Jedi, which help you get GMY. They are effective in early arena, but you will have to transition away from them at some point.

2) Nightsisters
This is a new one I've been working on, and have kept me reaching top 20 through level 50 (beyond that the whales are too good to beat right now). Similar to Phoenix, they are all in easy reach: Daka from Cantina store, Acolyte from cantina, Talia from starter, hard, and cantina, and Asajj from Arena. Until I'm able to save up 2000 crystals to buy Zombie shards, I'm running Royal Guard as the 5th. This is a strong early and late arena comp -- and once I also acquire Talzin, will likely keep me in the top 5 until people build end game teams. While I'm currently struggling against higher star/level/gear Phoenix, I easily beat similar comps. They also help you get Talzin and Zombie/Spirit shards from events later.

3) First Order
These guys take a little longer to get rolling -- Kylo Ren Unmasked unlocks from the third cantina zone, while Kylo Ren and Executioner are also in Cantina. Officer is in the Cantina Store, Phasma is in the GW store, and FOST and FOTP are hard farms (but unlock easily). I would start with KRU to 5*, then work on Executioner. Start out with KRU (L), Phasma, Officer, and then add in additional FO units as you unlock them. Since Phoenix don't have heal immunity, and don't hit particularly hard (except Ezra), KRU is able to heal through them pretty easily with his unique, and you can counter Phoenix by level 50 or so.