Just wanted to know how people colour correct (for example using PS RGB channels).
I haven't got a fool-proof method yet and try to use lightroom with RAWs.
In Lightroom I pick the White Balance preset that seems most suitable (Cloudy, Daylight etc) and if it looks at all odd I try adjusting the Temp slider until it looks ok. If I can't get it to look right I may try adjusting the Tint slider
very slightly. I don't alter individual RGB colour channels in Photoshop - I found it very difficult to get good results and very easy to get bad results that way, and I quickly gave up trying. Someone who understands colours better than I do might well be able to get better results though.
Incidentally, there is "correct/right/accurate" and "looking right/nice/appealing". While out shooting you can use a white card to take a reference shot that you can use in post processing to set the white balance. As long as you don't have mixed light sources, (e.g. artificial lighting indoors with natural light coming through a window, or e.g. natural light outdoors and flash), a white card should give you a pretty
accurate white balance. However, as to whether that accurate white balance would be the
best white balance to use in terms of how you would like your image to look, only you can tell. (Martin Evening is quite interesting on this subject in his Lightroom 4 book.)