1st, Save your coupons until you have close to 2000, don't spend any. I know this may sound counter productive, but this is so you can buy Cave Key Packs. These are SO worth it. Also don't use your keys until the rune rebate. This will give you a big boost in your runes.

Then focus all your monthly points for refines. You don't need to spend coupons on the low lvl ones. Get all your gear to lvl 4 refinement.

Then focus on Battle Armor to Rank 3 by monthly points.

Save your seal scrolls for the Jinchuriki treasure or if you want kage ninjas save them for that treasure.

Do as much as you can in-game, I done this as a f2p and I am one of the top 5 ninjas on my server.

And finally, join a new server at the start of the month, or if you want the sign in ninja currently find one sooner than that.

Couple problems, the only refine runes you should get are Medium refine runes from group shop, however that is over priced so you're better off just getting them from weekly events or even monthly event, you'll get plenty of low lvl refines from events and Monthly Event.

Next, you'll get a lot of magatamas for free no sense in wasting coupons on them, from events to ninja exam

You c*so easily get to Rank 3 Battle Armor without SA, but yeah SA helps but it isn't required by ignoring SA until you're max max stars on your team you can easily focus on getting fragments first.

I'm generally always out of stamina so I never do SA lol (level 14 and almost rank 4 on my BA) mostly cause I generally focus on awakening and gaining frags :p

Too bad that doesn't work anymore :P