They were probably dressed in the habits of Judean peasants, and not with any marked difference from those of the same rank in life.

And that they were dressed plainly, we have every reason to believe, from the censures, which some of them passed on the superfluities of apparel.

But christianity has no where recorded these habits as a pattern, nor has it prescribed to any man any form or colour for his clothes.
But christianity, though it no where places religion in particular forms, is yet not indifferent on the general subject of dress.

For in the first place it discards all ornaments, as appears by the testimonies of St.Paul and St.Peter before quoted, and this it does evidently on the ground of morality, lest these, by puffing up the creature, should be made to give birth to the censurable passions of vanity and lust.

In the second place it forbids all unreasonable changes on the plea of conformity with the fashions of the world: and it sets its face against these also upon moral grounds; because the following of the fashions of the world begets a worldly spirit, and because, in proportion as men indulge this spirit, they are found to follow the loose and changeable morality of the world, instead of the strict and steady morality of the gospel.
That the early christians understood these to be the doctrines of christianity, there can be no doubt.