before and after pp, does your photo become better?
so in most cases of selective colouring, the reason for pp is to make the subject stand out. usually, the coloured thing will be very prominent and grab all attention immediately, popping out of the background
here, it doesn't. the tones achieved do not stand out.. in fact the background ends up becoming more overbearing
on another note, the person is looking very ghostly, not sure if you want to give such a feel
maybe if you put up the original, people can suggest what pp exactly to do.. but personally, i do not think the photo is well taken in the first place.. it could be pp, but the flash here (if there was) looks very very strong
Selective coloring can be applied here but just keep it to the flowers or other objects where the color is bright or colorful. If you do selective coloring on humans, they just look dead unless it's very well done.
Also the whites is blown, the flowers has lost all it's details.
your selection technique needs alot of work, some parts of her arm is also b&w
anyway the bg is still too distracting and her line of sight is leading to nowhere
i'd convert the whole thing to B&W and blur/motion the bg also adjusted the tones to make her stand out
then added more bg on the right for her line of sight
added some graphic elements for point of interest
on my monitor, it looks like you have a slight greenish cast in your ps'ed photo. would suggest correcting the colour cast to achieve more natural looking skin tones, as well as the contrast and saturation to bring out the colours more vividly, particularly the pinks and reds. minor suggestions would be a slightly tighter framing at the top of the image, and some touching up of the teeth to make them look more even.
Obviously you didnt do layers, either that or your layer mask was done with a terribly lazy job. Feathered too much such that the desat bit has eaten up part of her shoulders. Slip shod work will give you slip shod results.