A. If the Orthodox group you join goes in for black clothing, you should be guided by them. But it’s not so much the colour that matters as the tidiness and modesty of how you dress.
Shir HaShirim 1:5 says, “I am black but comely”. The original meaning of “black” in this verse is swarthy or sunburnt, but the Midrash gives it many more meanings. In today’s Jewish world one might suggest that even if a person wears black they should look smart and clean. The rabbis go so far as to say that a talmid chacham who has dirty marks on his clothing deserves to die (Talmud Shabbat 114a). Whatever colour you choose, don’t be sloppy.
Secondly, don’t be immodest. Parts of the body that are normally covered should not be flaunted. Isaiah (3:17) regards it as a disgrace if someone “lays bare their secret parts”. As I used to say to brides, don’t come to the chuppah dressed (or undressed) as you would on the beach. Whatever clothes you wear, don’t let your body language be provocative. The same chapter of Isaiah (verse 16) speaks of people who are “haughty and walk with stretched-forth necks and wanton eyes, walking and mincing as they go…”