pondering color : risky colors that work...

i feel like it's always a little risky to throw a bunch of color together in one room...what if they clash? ... equally risky is choosing one color with major personality, like a mustard orange-yellow, to put on the walls... such a color could be overpowering...somehow though, i love both of these rooms with risky paint colors... someone please help me make colors work like these do (of course Martha can do it)...