Dynamics change a lot as you progress later in the game.
Credits are plentiful early, about right mid then you will always, always be broke later.
Gear is easy early, about right mid game then gets insanely hard.
you will generally only level a toon a couple days every few days assuming you do moderate mod leveling unless you have a scoundrel team. You get as much from that team as all other credits in all all other events combined in a week. Great if you had then, scrambling if you didn't and screwed if you don't.
You will probably average a single purple gear slot for a single toon daily assuming you get varied pieces from hard nodes, a little farming and raids. Targeting a single slot will take maybe 10 days, longer for raid gear, like 2-3 weeks per slot.
Sim tickets, buy some early game, mid about right then end game you will have hundreds and thousands.
MK 1&2 mats, scarce early, about right mid, thousands at end gane.
MK 3 about right early and mid game, scarce end game.
Omega mats, scarce all the time.
Toon shards are ironically the easiest thing of end game.
The key is ignore the constant pressure to get lots of different toons. They want you to have lots of toons making it extremely hard unless you start dumping thousands of bucks in the game.
Since they are incredibly unbalanced, you see the same toons at the end game. Key is keep your toon count low so focus on what is best.
Arena: Droid or meta usually involving mostly rebels like Lando, STH, Wiggs
Raid: TM reduction, they solo it everyone else does a little damage. Teebo, EE, QGJ, Rex (200 bucks buy only) 5s or Phasma, Dengar, Ewok Scout and a couple others but those are the main.
Most Jedi are mediocre except Lumi, QGJ and JKA. Yoda is a trap! Makes you get lots of mediocre toons for a mediocre toon everyone thing must op but isn't.
EP is insanely good, and you need Rebels which are insanely good so...don't go for yoda.
Scoundrel team is a must. Lando, Chewie, STH, IG88 are the obvious. Dengar mostly because he has other utility, raid. Chewie is better than STH because he can heal and get off taunt before he dies but everyone has maxed STH due to him being the op toon for arena. Really just IG88 and Lando kill everyone, others are there to absorb hits.
Then there are some that are just so good they are useful in all but the best synergy teams like Lumi, Rey, GS and RG. Maybe Chewie.
So key once again is narrow the toons you focus on as much as possible and pick carefully because some you may level because you like them but find out after months of effort they are utterly useless in the end game. I'm looking at you yoda.
After you get your core, then develop your secondary to play around with.