Generically speaking (and not referring to the part about the redness--for which a green-toned concealer would work) I honestly don't agree with the concealer-lighter-than-foundation theory. IMHO, the lighter parts, especially if under the eyes, may work in photographs, but to me they look a little bizarre when face-to-face and sometimes actually DRAW ATTENTION to what one's trying to conceal. Plus, with time (and especially in warmer weather) the concealer tends to "melt" into the rest of the makeup and any effect ends up getting lost.
To me, the best way to conceal something is by camouflaging it with the surrounding colour... in other words, match the concealer to the rest of your face. Leave the darkening/lightening tricks to the highlighting and contouring products.
Also, we shouldn't feel as if we have to hide every single "flaw"--wrinkles, freckles, eye circles, etc--sometimes trying to obsessively hide minor and "character" details results in drawing more attention to the area and in an overly made-up look (unless you're looking for something dramatic). Let's leave the total airbrushing to the freaks on the magazine covers and enjoy and enhance our natural beauty for what it really is: natural and beautiful.