Here is a great tip for saving a weak channel.
Open an image that contains something red (ex: fall leaves, strawberries, persons face, etc.).
Take a look at the channels by using apple or alt (pc) and 1 (red), 2 (green), or 3 (blue).
You can get back to the full rgb preview by hitting apple - tilde (~).
You should notice that the reds in the image show as white in the red channel with not much detail in them.
If you look at the green channel you should see some detail and texture in these areas.
Blue usually looks quite broken up but look just to make sure.
What we are going to do is put some of this detail from the green channel into the red channel.
First duplicate the background layer (drag the background layer down to the new layer icon in the layers pallet.
Next, with the background copy layer highlighted, hit apple or alt 1 to preview the red channel.
Now go up to the image menu and down to apply image.
In the layer box choose background, in channel box choose green (because this is the channel we want to take the info from), and in the blending box choose normal (you can play with different blend modes later).
Hit ok and then hit apple - tilde to get back to the full rgb preview.
In the layers pallet change the blending mode of the background copy layer to luminosity, very important.
Then lower the opacity of that layer to 0 and bring up gradually.
You should see quite a difference in red detail.