I need help with my team compositions.

Like the answer said, I need help. Here are my servants. All SSRs or SRs are NP1 unless I state otherwise.

Saber: Mordred Lvl 78, Altera lvl 50, Altria Alter lvl 24, Caesar lvl 40, Bedivere lvl 30.
Archer: EMIYA lvl 70, Atalante lvl 66, Kogil lvl 43, Robin lvl 40 and Touta lvl 1, Arash lvl 1
Lancer: Dark Eli-Chan lvl 1, Cu lvl 66 and Proto Cu lvl 60
Rider: Ozy lvl 60 NP2, Iskandar lvl 60, Kintoki Rider lvl 70 NP5, Anne & Mary lvl 50 NP2 , Medusa lvl 54
Caster: Nitocris lvl 50 NP2, Iri lvl 50 NP5, Blavatsky lvl 70, Medea Lily lvl 40, Medea lvl 54
Assassin: EMIYA (Assassin) lv 77 NP2, Trash (aka Stheno) lvl 1, Serenity lvl 1, Kotarou lvl 30, Hundred Personas lvl 30, Jing Ke lvl 50, Cursed Arm lvl 48
Berserker: Lancelot lvl 64, Heracles lvl 75, Lu Bu lvl 1
Shielder: Mash lvl 61.

Any tips on how to form effective teams are welcome. I already cleared Camelot, but I want to start preparing for future singularities and events.
Also, any future gachas I should save quartz for gameplay's sake? My goal is to one day have on my posession every Saberface there is. Every single one, including the saberfaces that are not Arturia. But for gameplay's sake is there any future servant that would fit in greatly with what I already have?