A new player looking for advice!

I'm new to this game, but I have dabbled in gacha before and am aware I should be conscious of what characters I should invest in/team compositions. Does anybody have any advice on this front? I don't want to spend a bunch of time and resources only to not end up using that character later on. The characters I have are:

Lilya (lvl 30), Sonetto (lvl 25), Erick (lvl 25), Eagle (lvl 25), Leilani (lvl 22), Click (lvl 8), Matilda (lvl 8), Necrologist (portrait 1), Satsuki, Bkornblume, Baby Blue, Oliver Fog (full portrait), Mondlicht (portrait 3), Rabies (portrait 2), Nick Bottom (portrait 2), Mesmer Jr. (portrait 1), Poltergeist, TTT, Cristallo, APPLe, Pavia, and various other lower-level characters

Thanks in advance!