A proper fop can never have too many socks. If essential it is to have a wide variety of shoes (and it is), then it is equally essential to have a fine collection of socks. Socks of the average sort, like black, white, brown, and navy, are but the bare minimum. Utilisation of subtle matching comes of as quite foppish (just don't overdo it). Matching one's tie with one's socks, providing it does not conflict with shoe colour, is a way to draw attention to detail from even the sort of people who are less inclined to notice. We advise adding a splash of colour to a more neutral, plain outfit with the artful usage of bright socks in hues like bright blue, red, or emerald green. Yellow and pink may be pushing it a bit, though paler shades of these colours could be put to use if tied into the proper togs. As with fine wine, use this technique in moderation to avoid looking silly.
Another important (and perhaps more obvious) necessity is the tie. One simply cannot own enough ties. And, of course, one must own a selection of repp ties if one is to be taken seriously as a dandy. Avoid overly colourful patterns and anything that could come off as gaudy. Sometime the simplicity of a solid colour does the job. Regemental and collegiate ties are also very telling of breeding if they are appropriate to wear. Alternatively, stripes in family colours are nice. Apart from the common neck tie, a good handful of bow ties is strongly advised and, if you're especially dapper, a few ascots and, of course, cravats. Nothing beats a white satin cravat with a fine waistcoat.
It might also be added that a good set of sock braces is next to essential in keeping a pristine appearance by keeping those socks wrinkle-free. I can only imagine the embarassment one might endure by flashing a pair of socks bunched up at the ankles.