Hair color product web sites offer the entire range of hair color available with them and what can be done with it. However, do remember that they are using professional models (with amazing skin) and you would need to discount some of the ideas that they demonstrate. The official web site however, does help you get the right shade and that is very important before you decide your hair color.
The second stop on the internet is an Expert's page....most likely to be on lifestyle web sites which tell the ground rules of which skin types goes with which hair color etc. Don't bother to read too many of these as each one of them is likely to have their own version of hair color palette! Once you have short_listed a range of hair color options, try looking for pictures of people with similar coloring and how they would look in it. Many salons have sophisticated software which helps conjure up an image of you with the hair color and it might be worth the money you spend on it.