1. The clothes that one wears should not be tight fitting or body hugging. One should wear loose clothing.
2. The clothes should not be so thin and flimsy that the satr becomes exposed.
عن أبي هريرة قال قال رسول الله صلى الله عليه وسلم صنفان من أهل النار لم أرهما قوم معهم سياط كأذناب البقر يضربون بها الناس ونساء كاسيات عاريات مميلات مائلات رؤوسهن كأسنمة البخت المائلة لا يدخلن الجنة ولا يجدن ريحها وإن ريحها ليوجد من مسيرة كذا وكذا. (مسلم 2/383)
Hadhrat Abu Hurairah (Radiyallahu Anhu) reports that Rasulullah (Sallallahu Alaihi Wasallam) said: “There will be two groups (in my ummat) who will be punished in Jahannum. These two groups I have not yet seen (i.e. they will emerge after my demise). One group will carry whips with them resembling the tails of cattle, with which they will (oppressively) lash the people. The second group will be those women who will wear clothes yet they will still be naked (i.e. tight fitting or flimsy clothing), they will attract men to themselves, and they themselves will be inclined towards them, their heads will resemble the humps of the Bukhti camels (i.e. they will wear buns which will be high like camel humps). They will not enter Jannah nor smell its fragrance, despite its fragrance being able to be perceived from a great distance away.
عن هشام بن عروة أن المنذر بن الزبير قدم من العراق ، فأرسل إلى أسماء بنت أبي بكر رضي الله عنها بكسوة من ثياب مروية وقوهية رقاق عتاق بعدما كف بصرها ، قال : فلمستها بيدها ثم قالت : اف ، ردوا عليه كسوته ، قال : فشق ذلك عليه وقال : يا أمه ! إنه لا يَشِفُّ، قالت : إنها إن لم تَشِفَّ فإنها تَصِف . فقال : فاشترى لها ثيابا مروية وقوهية فقبلتها وقالت : مثل هذا فاكسني . (طبقات ابن سعد 10/240 )
It is reported regarding Hazrat Asmaa (Radhiyallahu Anha), (when she reached old age), her beloved son Hazrat Munzir bin Zubair (Radiyallahu Anhu), after returning from Iraq, sent her a cloth as a gift which was of very fine and superior quality. She had lost her sight, and so held the fabric in her hand feeling it carefully. Then with disappointment she said: “Return the gift to him.” When the cloth was returned to Munzir (Radiyallahu Anhu), he was hurt at this. He came to Hazrat Asma(Radiyallahu Anha) and said to her: “O my mother, the cloth is not transparent! (Hence, it is fine for you to wear).” Hazrat Asma (Radiyallahu Anha) replied: “Even though it is not transparent, however due to it being tight, it will still reveal the shape of the body.” He thereafter bought for her common garments made in Marw and Quhistaan. She accepted them saying, “It is these types of garments that you should give me to wear.”