Farm mods, but sell any that don't have speed showing. Mods eat cash like crazy. You could try to peek at the secondary slots that aren't showing yet for purples and blues before you throw them away, but the whites (with nothing showing) or the greens (with one secondary showing) take too much cash even to just check to see if they'll develop a speed secondary. If you do this right, you can pick up a smattering of good mods without siphoning off so much cash that you're unable to do other important things, like level up characters.
Also, you need to work on bounty hunters for both Chewbacca and the Millennium Falcon. They are long farms, so might as well start now. I hope you're using all your GW currency for ships, especially Geonosian ships. The Geos are good ships - not the greatest at the beginning, but still good, and when you finally pair them with Malevolence, Vulture, and Hyena, they become truly awesome. So you might as well be going for Geos now. You need 5x5* Dark Side ships to get Executrix up to 5*, and you need Exec t 5* to get zetas. You probably have Vader and his ship at 5* each, but keep working on them. TIE Fighter Pilot's TIE and Kylo's TIE Silencer are good ships for the zeta challenge as well. The Bounty Hunter ships work, but they're going to take too long. You'd miss out on months of zeta farming if you waited for them.
I always recommend spending a good bit of extra effort on Fleet Arena because it's definitely easier to finish top 5 in Fleet Arena than it is to finish top 20 in Squad arena, and the 300-400 crystals you get per day from your fleet arena finish will fuel a lot of growth.
Also, complete GW every day. It really helps a lot. But nothing but ship shards in the GW store until you notice that you've got enough of them finished that your currency has started to accumulate. Once you have 4k+ you can spend on whatever characters you want until you're down to 2k. Always keep 2k GW tokens on hand for those ships that show up rarely in the GW store. If you're having trouble completing GW store, you can get help with that as well. The most important thing to know, however, is that you should be using 5 different squads on the first 5 nodes so that when you battle your way up to 9-12 you have more than one squad with pre-loaded Turn Meter. Having all your characters go first can allow a team to beat an enemy squad it would normally not be able to touch. Make sure all your GW squads have some healing ability and hopefully some protection regeneration as well. Even a 3* Geonosian Brood Alpha can turn the Geos into a constantly regenerating, nearly unstoppable machine. Phoenix will do for some parts of GW because of their own regeneration. First Order is useful in GW at your level. Jedi Knight Revan + Grand Master Yoda + Jolee Bindo (yes, just the three of them) will allow you to stomp GW so hard you'll never need another squad again...but only after you have about 3-4 zetas on the team, so you're a long way off from that yet.
Are you in a guild that Sims the Rancor? Or one that still plays it out? If you care more about your growth, and you're willing to play every day, the best thing to do is join a guild that's willing to take under-80-level players on board for the raid tickets. You have to commit to spending 600 energy per day, but in exchange, an established guild that Sims Rancor will give you much better rewards than you're likely to get otherwise. In particular you'll get Raid Han to 7* much faster than otherwise. Also, if you're in a guild that is not simming the Rancor, they may not be doing Heroic AAT yet. No time like the present to start collecting those General Kenobi shards.
Aside from all that, never, never, never forget that it's a game. If anything that I've said seems less fun to you than doing something else, always to that other thing that is more fun. This game has a serious grind. It takes weeks to months to accomplish your goals, and there's always another goal waiting behind that one. If you're not constantly prioritizing fun, the game will simply become work, and that's when you'll quit. Because this is supposed to be fun. it's not supposed to be work.
Best of luck!