My Suggestions for players who want to grow optimal without spending money.

1) Newer use R-Gacha tickets donate them all 1 at a time. Players get one R-Gacha from daily quest.
2) Don't Leave area 1-3 until all your girls incl. all girls from Gacha are level 100. Then you all spins just cost 1 energy.
3) Newer let you energy hit max. Then you get 24*60=1440 spins + extra spins when you gain a level.
4) Make cetain that you got 0 energy when you gain a level.
5) Finish all daily quests other then get 3 SR-girls every day. Not hard with 1440+ daily spins.
6) Use N-Gacha to do the get 3*N-girls, and get 2*R-girl quest.
7) Dont buy N-Wild in ship.
8) Only combine 10 N-Wild into a R-Wild if all your N-girls are level 100.
9) Use an invite when you make you account to gain 200 gold instead of 100 gold.
10) Get 5 friends to make an account and gain 500 gold
11) Make a 2nd account to explore the game and see the films.
12) Have max number of friends to get a high mex energy.
13) SR-gacha cant be donated so it can be used but only use when you have problems finishing the 3*SR-girl quest.
14) The Chance quest give a R-Gacha which almost alwasy can be traded for a Wild3 or a limmed girl so it is the most importaint quest to fin
15) N-wild, R-Wild, Wild1, Wild3, Wild5, Ex-Wild, N-Gacha, Candy are not worth donating
16) Buy 3 * energy flask + 3* puddings for 60 gold the first 3 days.
17) Buy 2 half puddings for 10 gold everyday.

How fast you will grow:

1440 spins per day give around (144* 3-Chance, 144* 3-Gift, 144* 3-Exp, 144 * Pero, and 864 miss.

Exp per day excl. leveling 1584 Exp/day
Pero (3-Chance): 57600 P + (3-Pero): 7200 P + (Other spins): 6440 +(dayly quest) 18000 = 89,280 Pero/day.
Gift send 144: If half of the is returend 72 N-Wild per day.

It should not be hard to get 200 N-Girl levels per day if not all your N-Girls are maxed.
When all N-Girls are level 100 your R-Girls will gain levels much faster.
60-100 R-girl levels per day should be posible when all N-girls are level 100.
When all your all your R-girls are level 100 you SR-girls will gain level fast.

After 2 weeks all you 25 N-girls should be level 100. After 2-3 more weeks all your R-girls should be level 100.
Further 2-3 weeks all your girls should be level 100. Then unlock next area but dont move further untill all your girls are level 100.