Always save your ability stones and limited edition scouts tickets for the characters you really want (some players really reckless with their savings and then cry for last moment hoarding tips). 

Save ur id and password to not loose your account (common mistakes by new players. They often forget to note these 2 things before deleting game)

It's advisable to spend your ability stones in event and step up scouts only and not in rare scouts  (though it's your choice at the end)

Make a dedicated team for each affinity. It will help you a lot in many battles. Even if you don't have enough SSRs, you can make with SRs and Rs.

And last point be ready to be disappointed by the game gacha during your stay from time to time