for f2p player, best thing u can do is convoy and plunder. You will got 2 free convoy if u are top 50 (non-merged server) and top 100 ( merged server). For plunder, u better have another account in a different guild on the same server so u can success everytime u do ( the difference for plundering level is 15).

Try to spin the group wheel max daily. U can do this by contribute to ur group by coin so u can obtain group contribution for spinning. On the lucky day, u can obtain 50-80 cps easily.

As Joshtaku said, group summon 2 times a day - twice a week. so u have 4 attempts each week, max is 40 cps each attempt. 40 x4 = 160 cps from summon.

Log-in rewards

Puzzle on weekends activities

U c*so obtain cps for free from weekly event:

+ Mount Myoboku mini-game (3 attempts every day)

+ Treasure of Sage ( got 5 free key daily from doing Plot)

P/s: my last advice that, Shisui has been out of meta. u better save ur cps and spend on a meta one like naruto 6p , hiruzen , AGK, 5 kage madara (with either deidara or jonin minato). I personally dont like naruto 6p and dont have any intention to get him, but he is the cancer meta now and it is ur call.