Tip1=...superimpose the images. Copy image 1 to the clipboard, past it to the image 2 and adjust the transparency on the toolbar. The more the transparency rate is, the more image 2 shows through image 1.
Tip2=...add transparent text to your images û after you clicked OK in the editing window set text transparency on the "options" bar.
Tip3=...select or delete every almost monochrome object or the background, tuning the tolerance. It doesn't change the actual image, but "rounds" colors for "Magic Wand", "Fill" etc.
Tip4=...create your own special effects. To do it just select the "Effects->Transformations->New" menu.
Tip5=...draw straight lines û click on the "Line drawing" on the toolbar (next to "paste").
Tip6=...select multiple regions. Select any region. Then hold shift and select other region. Then you will have both the regions selected.