What halachic restrictions apply to wigs for married women in halacha?

As any clothing, especially a married woman's wig- which is specifically geared for modesty, it must be modest and could be attractive but not "attracting". There are many, especially Sefaradim, who don't support the idea at all, especially if it's difficult to tell that it's not her real hair, but many (even sefaradiot, like the Yaskil Avdi) are lenient, and surely outside of Israel, the custom is to be lenient. It's better if it's not from real hair, but there are authorities who allow that, as well. In addition to the fact that it's already known and accepted that many wear wigs, my wife tells me that women can always tell that a wig is not her real hair, so accordingly, it's not mar'it ayin. In Israel, in most places it's accepted not to wear wigs, but especially if the woman is a ba'alat teshuva, this mitzva may be difficult for her, and it's actually better to allow it (unless it really doesn't bother her), for "her (=the Torah's) ways are pleasant ways, and all of her paths are one's of peace" (Proverbs 3, 17)! It's also obviously better to wear a wig which covers your hair properly (leaving out just that permitted 1 tefach= 2 cm. across the width of one's face if she wishes) rather than to wear a minimal "symbolic" or partial hair covering.