Ill try that uploading site later since im not on my main comp.
But i think i use the default settings? I just pentool inside the render using curves and such, then contect em, make selection, select inverse and then use the eraser tool.
But some of those render are when i first started rendering, I know some may not be perfect but someone might find some use for em.
theres ur error. just press Delete
Also i would suggest creating a layer, coloring it black and put it under the picture ur trying to cut. Will show white spots and flaws.