Focus on characters/teams that will help you increase you income of resources to further develop your roster.
I'd recommend to find a guild that does the Separatist Might TB (GET II and Wat), farms Heroic STR (g12+ gear and Traya) and raids frequently (generates more than 20k tickets a day) ASAP. You will benefit greatly from the extra rewards.
You already rank consistently in top-10 (or even top-5) in fleet arena but you won't for long without Malevolence or Negotiator. Start farming the 5 Separatist ships and 3 Geonosian pilots ASAP. You will need them to remain in top-10 in fleet arena and for a Malevolence fleet (along with GG). If you have all 5 geonosians geared and ready for the Wat mission in TB it Will help you enter an even stronger guild.
For GAC (based on your GAC-history):
+* If you want to use your NS against geonosians you will need zombie and zetas on Talzin's lead and Asajj's unique. With NI and JKA your NS will be able to solo phase 3 of hSTR. However, apart from Asajj the NS aren't required for any journey character or GL.
* A zeta on EP's lead will take your empire team to a whole new level.
* A zeta on Bossk's lead will make your BH able to beat NS teams (and also help you on higher tiers af Chewie's event and in fleet arena).
* Cassian's U-wing will improve your rebel fleet greatly (no need to gear the pilots). Gearing up Han and Chewie will as well.
When choosing your first GL I'd recommend one that solos hSTR even if it's not the strongest one for GAC.
You may as well buy shards for Dengar, Logray, Rex, GG and such already. You will need/want them eventually.