The color choices differ for every person. If you can find cards on blogs, or in the gallery that you like, and think you would want to do those types of colors, or stamps, then you can see what they used and pick from those.
As for me, I prefer the Cool Greys. If I had to pick a grouping from each color, it would probably be the Y2x family, YR2x, G2X, R2X, B2X or B9X, BG7X, YG6X, RV3X, V0X, abd BV0X. From Es, I would get the E000, E00 and E02, but then also the E3X family for browns. Those ar ethe ones I lean toward personally. I know others thought that don't use those families, but go for other shades.
Unless you have some you can really blend with, then it is hard to get a feel for them. I know a lot of people do the one of each color, but then you don't get the true effect, because only certain colors really allow blending cross families (Some YGs and Gs blend really well and some YRs and Ys or Es do as well). Another mistake I hear about is people buy mid-range colors, or dark colors only. That was my initial problem with reds of all things. I had R24 and R29. While that blends really well sometimes, I didn't really get a great effect with them until I added the R22 as the base, and then toned over with the R24 and a touch of the R29.