To be honest
Lee, I often have a hard time too to remember what what every blending mode does. Many times I just scroll through the list until I have the effect I want. After a while you will notice that you start to memorize how some of them work.
Here, take a look at this thread;
http://www.photoshopgurus.info/forum...light=blending
Or this one;
http://www.photoshopgurus.info/forum...light=blending
Blending modes are also very useful to add non-destructive effects;
http://www.photoshopgurus.info/forum...light=blending http://www.photoshopgurus.info/forum...light=blending
And something else Lee, blending modes can be used in a lot of places;
layers, brush tool, pencil tool, clone tool, pattern stamp tool, healing brush, patch tool, gradient tool, paint bucket tool, etc, etc.
As soon as you see the word
Mode in your tool bar, then you'll know that you can use blending modes for that particular tool.
My advice is not to concentrate too much on the blending modes that you can use in combination with these tools, but rather
focus on the layer blending modes.