You may easily correct colouring defects by programs like Irfanview, Photoshop, various corresponding Microsoft software for managing pics, ...
Try to modify the colours mix. To much yellow usually means too much red and not enough (brightness or gamma) blue.
For the other question: You will only be experienced and be able to improve by taking your OWN pictures.
regards
I use the much simpler Photofiltre
software for all my picture modifications. It's much less complex than Photoshop and is completely free. You can get it here:
http://photofiltre.en.softonic.com/Here is your
Faustina after clicking a few Photofiltre buttons. OK its unsophisticated editing but its a quick repair job. Better than the original and better than the black and white. I nudged up the green and
red, nudged down the yellow,
reduced colour saturation a touch, increased exposure and colour-contrast a little. No sharpening. It took just a minute.
I think your photo is better than the dealer pic in this case, but even if they are only about the same its much nicer to use your own photos than someone else's. More ownership.
It ALWAYS helps to take your photos on a
standard 18% grey-card background. The intent is that you use the grey card to set up the exposure
http://en.wikipedia.org/wiki/Gray_card but its simpler just to drop the coin on the card and photograph it there. It tends to
help the colour balance a lot especially with
cheap cameras. Domestic home-made alternatives don't
work well - apparent grey surfaces are often a mix of colours - so spend a few dollars and buy a card.
