Short version:
Player level 73 — arena team is 60—69. Always have your arena team at max level.
Make sure, that your guild is doing heroic pit raids.
Replace Kylo Ren in your arena team. Get ST Han in there instead. That will make a great team to take you to top—500 (maybe even 200 depending on your shard).
Move your best mods to your arena team. Use the filtering option on swgoh.gg to find and sort them out. F.ex. all your best speed stat mods should be on your arena team — not on random other toons:
https://swgoh.gg/u/ishmozthepresident/mods/?stat1_5=1
Also make sure to do all mod challenges available to you at least once to get some more starter mods.
Phoenix is great, but don't let them interfere with your current farms (Wedge, Lando, ST Han, Boba Fett). Get them to 7* first. Farming ST Han will also help your scoundrels do higher tiers of credit heist. You obviously need those extra credits for your arena team.
Good luck.