I use mine mainly for colouring Magnolia stamps. I tend to lean towards pastel colours instead of bright but I do seem to add more n more bright colours. I think its best to decide what you want to use Copics for first. Then, see which teint you prefer (pastels, bright, vintage, monotone, ect) Start from there. Some shops have testers to see if you like the colour. Do keep in mind, once dried, it's slightly different in colour than when you first applied. Just a few from each colour will work cause you can darken the colour by going over the same area with same Copic colour. As for Greys, I prefer the W colours, they are a bit of a muddy type of grey and I also like the C greys, they are perfect for colouring steels.
If you go to their site (Copics), you can get the colour charts. You can download it, print it ect.
I agree with the suggestion above, start with some colors you like and buy a series, like 02, 04, and 06. and a colorless blender. Numbers about 2 away from each other are perfect. I started with aqua, yellow, and orange because I was wanted to color fish. I also started with 3 shades of gray. Which colors you start with are personal preference.
If you don't want to blend, then the sets are good. Or they are a good way to add some basic colors to your blending ones - just in case you need some purple sometime. They used to sell more single some here, but now it's mostly sets. Hopefully they will bring back the single ones.
I never use the blender, for some reason, when I use it, it either fades the colour completely or it makes the colours bleed outside the images. I'm a inside the lines colourer and I serously hate bleeding outside the lines. I use white correnspondence cards and DCWV cardstocks. Both work fine for me. I stamp with Memento.
Copics do come in blending sets - there is a new 3 colour set, but they also have 6 colour sets that specify whether they are good for skin/florals/pastels etc. I own a few, but switched to ShinHan Art Touch Twin Brush markers which have basically the same tips as the Copic Sketch without the price tag.
I have a post on my site that gives you a shopping list for beginners you can also check out cara miller just type her in the search on google and she will pop right up. I don't recommend buying the sets because they don't give you the copics you need in order to blend and blending is what copics are all about Copics make me so happy!!!