Ciao has is the same exact thing as Sketch but smaller and holds a little less ink. They're a bit cheaper too, but they are also refillable and their nibs can be replaced to.
Since you like to draw people, earth tones would be helpful for the skin. I could say some of my favorites, but what works for me might not work for you. I also buy my markers individually, but if you really want a set Copic does have some small ones like for skin, water, pastel, etc.
I am by no means an expert but I came across some lists for starters in various Copic blogs/websites. Maybe these will help you out;
A couple of start-out lists by different artists: [link]
Starter list with markers from every color family, two different links: [link] [link]
One tip that I can give you is using the Cool and Warm Grays for shadows and shading instead of darker colors. (It would depend on the base color if you use a cool or warm gray) I would also recommend getting Ciao's because they are basically the cheapest off all the marker types. That way you can get more different markers and so more colors.
I got the vast majority of my markers from eBay. I got a few of them loose from my local artstore when I was in a bind and needed a replacement quickly but most of them are bought online. There are also sellers with custom sets, like a nature or manga set.