@Boudewijn, am I right in thinking that you're cropping and resizing the sources down to 250x250 before requesting them? No harm in cropping them, but if you leave a space above the hair and below the chin, then the ensuing cut will only really be good enough for 180x180, irrespective of the size and quality of the original source

Yeah, so I shouldn´t crop it that much? Tried to follow your instruction and I, J, K and L said cropping

You should really have paid more attention to point (g) though - it's where the guide to cropping started