Manipulations using the RGB colour model tend to shift colours with little effect on saturation and brightness. It is thus often useful to carry out basic image editing before RGB manipulations.
Remember that switching colour spaces loses all the settings that you were using before without warning, so be sure that the curve, at least, is saved before switching to RGB. Sadly its not possible to swap between colour spaces to combine the effects if you want to do this, save the curves, save the image (apply or OK the transform, select the transformed image and open the color curves transform in the required colour space. As with HSV (& HSL) switching between channels within a colour space retains all settings generated so far.
For the RGB manipulations I will be working with the supplied brightness adjusted version of the colour image.
All the techniques discussed previously can be brought to bear in the RGB space, but are not always effective. You also need to bear in mind that these changes are working on V values of the selected channel, but the effects are combined by the RGB colour model into the output image.
I am only going to give an overview of the RGB manipulations. Techniques are similar to HSV but with different effects, experimentation is important and the limit is still your imagination. As in HSV there is a lot of space to experiment and also to combine techniques as needed to achieve your desired result.