The best tip for this game is to watch beginner guides on YouTube before installing.

If you don't know how to start from game installation to account creation, you'll be at a disadvantage from the beginning. Also, some coupons can't be used if you use others. New user coupons have time limits, and if you use a coupon, the cooldown is 24 hours. It's a game where you get screwed if you don't know these things.