General workflow

General application workflow should look this way:

Without raw decoder you won't be able to read RAW file. There are many raw processors available, I recommend RawTherapee http://rawtherapee.com/ but there is also simple ufraw or command line dcraw.

You don't need raw decoder when you shoot JPG or TIFF. It's recommended to use TIFF, not JPG, but sometimes you have no choice.

Without image editor you won't be able to perform local modifications, like clone tool, healing brush or "painting on mask". It depends on your style of postprocessing - and kind of photos.

My workflow

I use geeqie to select RAW files to edit, then I copy them to separate directory and start RawTherapee.

I open one image in RT, set some basic stuff (very often I don't change anything) then click "edit image in external editor" (with GIMP icon) which is configured (in RT preferences) to start delaboratory (just type "delaboratory" in "other command line").

In delaboratory I perform main postprocessing, I start with RGB curves, then go to LAB and work with AB then L. Then sometimes I go back to RGB and apply image to bring back some of the original colors. Sometimes I also begin with mixer + apply luminance to fix highlights in red channel.

Then I click "external editor" and GIMP opens, I duplicate layer and perform healing brush + clone tool, then I duplicate layer again and make a final sharpening with USM. Then I save .xcf and two JPEGs (full size and scaled down).

I am currently experimenting with sharpening in delaboratory instead GIMP, that's why I put HIRALOAM presets into delaboratory USM.

GIMP and G'MIC

Some people want to use delaboratory this way:

This diagram shows why it's not best idea. Both G'MIC http://gmic.sourceforge.net/ and delaboratory use 32-bit channels, but when converting them back to GIMP there is a huge quality loss.

It would be better to work this way:

But it requires G'MIC support in delaboratory. It is in my plans.