I love deep, rich blues with deep, rich shadows. This is a card I made a long time ago, and I might do it a little differently now, as my style has certainly evolved. But I still like the combination of these blues. I used B99, B97, B95, and B93. The B99 is a beautifully dark, rich blue which gives some great shadows.
Skin is always a tough one, and always a personal prefernce. Some people like a dark skin tone, while others prefer a pale look. Personally, I like a nice contrast with some deep shadows and I use E11, E02, E01, E00, R20. You can see how the skin under her bangs is shadowed and a deeper tone, with her cheek which is out in the sun, is much "brighter".
Another popular topic in Copic classes and always a personal preference as well. Real hair comes in an infinite array of colours, so the sky is the limit when colouring hair! There are some great manga artists out there who colour in blues, pinks, and purples too. My "go-to" choice for hair is E35, E31, YR20. Depending on how many times you layer, and how deeply you colour, they can look quite different each time. Here are two images where I've used the exact same colours for the hair and you can see how much darker the second one is.
I hope this gives you a few tips and ideas for your Copic colouring!