In the Name of Allah, the All-Merciful, the Mercy-Giving

All praise is due to Allah. Peace and blessings be upon His Messenger Muhammad.

If you have reasons to believe the clothes, you intend to buy are made of silk, then you ought to avoid it unless silk is only a small percentage of it or it is synthetic.

There is no need to raise this issue unless you have doubts; for in case of doubts, the Prophet (peace be upon him) has advised to avoid it unless we can confirm it to be wholly free from silk and hence purely halal.

Likewise, you may do well to avoid cosmetics which contain alcohol. Having said this, I must also point out that there are eminent scholars who say it is permissible to use cosmetics even if they had alcohol ingredients for two reasons: First, they are not intended for consumption. Second, the alcohol used has undergone a chemical change; hence it does not remain alcohol anymore.

There is no need for us to be rigid in such matters; the Prophet (peace be upon him)  has warned us against rigidity in matters of religion.

 Almighty Allah knows best.