1. Do not use moon tears(diamonds) to pull units in the standard banner, use only the common summoning scrolls.
2. Try to save your moon tears for event banners you aim for like Lamia and others. Lamia is amazing, her event banner starts on day 3 and you should save for her whether you're F2P or not.
3. Do not level up SSR units. Only 5 SR units in the beginning like Noah/Setti/Aiona/Jestel/Empousa. The game has a sync feature called transfusion tree that you unlock very quickly, and you can add the SSRs you want to use in your team to the tree and they will share the lowest level of the 5 synced units. SR units get their dupes very quickly which will increase their max level to 160(2 dupes max for SR). After about a month you will have SSRs with 3 dupes or more that you can swap in the transfusion tree.
4. With that said, dont hesitate to level up your first SSR until you unlock the sync feature, level reset is cheap and costs only 10 moon tears.
5. If you're rerolling, best reroll targets are Acappella, Starry-Eyed Aiona, Van Helsing or any ancestral unit(extra rare).
6. Don't waste resources on gear upgrades at first, wait until you get at least tier 5/6 gear. Gold will be very needed later on.
7. Idle time until the ritual rewards are full is 12 hours(moonlight tribute).
8. Upgrade the affinity of units you're actively using, it gives them stat bonuses.
9. Team formation is dynamic, but in general should have: 1-2 tanks, 0-1 healer, 0-1 buffer(like acappella), 2-3 DPS.
10. You will get resource items that gives you 1hr/2hr/8hr/12hr/24hr of idle resources(added image). Try to save those and use only when necessary, these items will naturally get more value over time, as your idle rewards improve with story progression.
Added a picture of the ideal picks for altar of invocation (summon wishlist).
Resource items
Altar of Invocation
