Maybe to may it clearer: So if you were taking red flowers, how would you take the shot and what adjustment do you have to made since obiously only the red-channel is affected ?
Expose less. Simple and painless.
(If you want to equalize the different channels, you can use colour filters, but it's pretty much pointless in the end. To get the brilliant colours back, you would have to undo the filtering later in software.)
If the red channel is blown-out, the PP helps since the fine details are lost ?
If you're talking about an existing overexposed picture, one can try to salvage some details by copying image details from the non-clipped channels to the clipped channel (based on the keen assumption that hue and saturation do not change much in the affected areas). This is how some raw converters salvage overexposed pictures. But this is only an emergency fix. And you will have to either reduce the saturation, or the brightness of the final image, as otherwise the colours cannot be represented (in the most popular colour spaces, that is).
If you have the choice, don't overexpose in the first place.
You cannot have a saturated colour patch that is simultaneously bright in RGB colour spaces that artificially restrict the brightness of the individual channels (such as sRGB or AdobeRGB). (Better RGB systems do not limit the brightness of channels and allow even negative RGB coordinates, but they are far from mainstream. The predominant colour space, i.e. sRGB, was not developed for good pictures, but for backward compatibility with legacy graphics systems. Adobe RGB is only a minor variation on sRGB and shares the same problems.)
You'll have the same dilemma with prints - you cannot have a colourful print that is as bright as the white base paper. Neither can you have a slide that is colourful and at the same time as bright as a blank slide. As the brightness goes up, the possible colour saturation shrinks tremendously.
If you want to circumvent the saturation limitations, you can rescale the brightness by declaring "white" as something less than the maximum you can get. I.e., keep your pictures a bit darker, and watch them with a dark (ideally black) background/frame.
"Dark" is relative. Let's say you limit your sRGB brightness to 0...127 (instead of 0...255). This will allow to maintain more saturated colours. Noone will be able to tell that your image is "too dark", UNLESS they see something brighter as a reference. If you keep the border/frame/background of your pictures dark, there is no such brighter reference. Try it on your computer screen in a dark room.
That's a big reason why projected slides, especially those with sparing exposure (-> helps saturation), look great to so many people when viewed in a dark room, and look sucky in a not-so-dark room. It also means photos will usually do better on dark (black) album pages (high key photos exempted). And it is also the reason why most better photo-related web sites use black (or at least a dark shade) as background in their colour scheme. Clubsnap's colour scheme, sad to say, is absolutely awful for photo viewing.
