First thing you should do is pick 1-2 roles you like to fill and then just pick up champs that fit into that.
Do you want to focus on AD carrying, playing AP, or jungling, etc. Pick up champs that fit into that. If you want to have a handful of champs for each role for trading or just in case, I say pick up another jungler that isn't Shaco, since he's less sustainable and simple and has issues contributing in teamfights.
For example. I like to primarily Bruiser top or jungle, so I try to pick champs that fit those roles (though I also occasionally try to pick up non-bruiser tops just in case).
Do you want to focus on AD carrying, playing AP, or jungling, etc. Pick up champs that fit into that. If you want to have a handful of champs for each role for trading or just in case, I say pick up another jungler that isn't Shaco, since he's less sustainable and simple and has issues contributing in teamfights.
For example. I like to primarily Bruiser top or jungle, so I try to pick champs that fit those roles (though I also occasionally try to pick up non-bruiser tops just in case).