Whether you order designs from 99designs or from an in-house designer, use this simple rule of thumb:
Your most valuable content should be the most contrasted.
Here's why. Bad designs are wildly different, but all good designs share one thing in common: they put your content first. As I am writing this, I realize that the text I am typing appears in charcoal gray or #4d4f51 while the title is all black. This is inconsistent at best, but not everything is lost for LinkedIn — the list of my last posts on the right is in a lighter gray #96999c and the editor buttons are even lighter than that.
The poster boy of good design, Boston Globe, displays text as black #000000 on all-white background #ffffff while their menu items have varying levels of greyness, from a rather dark #464646 on white to the same dark #464646 on neutral gray #eeeeee. This is good design — the most important thing Boston Globe has is news, and their news enjoy the most contrast you can get: all black text on all white background.However, many websites have their main content in a rather worn-out pale black, while surrounding elements are flashy and attractive. Check for instance BBC.co.uk, their content is shown in dark gray #404040 while the navigation is in all-black #00000.