TBH I only log on from time to time nowadays but my general guidelines in no particular order are
- Don't feel too pressured to complete events or grind for limited servants
- Rerolling is an option, I would probably go for Herc if you do, but it's not necessary
- Save for the characters you want even if it takes a while for them to come around, the game is generally not difficult and friend supports can carry you early game
- Don't spend too much money, maybe stick to the guaranteed banners or infrequent SQ if you do decide to open the wallet
- Arts loop supremecy