Note: Click on the Post Tags to see other posts regarding the guillotine (crop) tool after reading this.
To avoid repetitious tasks, it might be easier to make a sheet of alphas or elements and add the filters and scripts to it then cut them apart later. I save these sheets, like the one above, in case I need it again. I also name the lettered sheet after the font I used.
I space out the letters or elements so I can get a guide between them. To add a guide, drag your mouse (which will change into the move tool automatically) from the ruler down for a horizontal line or from the left across for a vertical line.
By selecting Image>Transform>Guillotine you'll get the image above, several new images or offspring of the larger image you added the guides to.
You can alter your image with bucket fills, script fu's, filters, drop shadows, layers, etc. all with the guides in place. Make sure before you use the guillotine tool you don't have the blue guides across a shadow or it'll appear in the next image over. Also, you might want to merge your layers first (do not flatten if you are wanting a transparent background). If you guillotine before merging, you'll have a new image in layers and will have to merge or export when saving.
One of the other posts talk about the naming of the offsprings.