Is it permissible for her to wear a little makeup when a suitor comes to see her?
Question

Is it permissible for a woman to wear a very little makeup when the suitor looks at her?.
Praise be to Allah.It is not permissible for a woman to show her adornment except to those whom Allaah has mentioned in the verse (interpretation of the meaning): 
“… and not to show off their adornment except only that which is apparent (like both eyes for necessity to see the way, or outer palms of hands or one eye or dress like veil, gloves, headcover, apron), and to draw their veils all over Juyoobihinna (i.e. their bodies, faces, necks and bosoms) and not to reveal their adornment except to their husbands, or their fathers, or their husband’s fathers, or their sons, or their husband’s sons, or their brothers or their brother’s sons, or their sister’s sons, or their (Muslim) women (i.e. their sisters in Islam), or the (female) slaves whom their right hands possess, or old male servants who lack vigour, or small children who have no sense of feminine sex. And let them not stamp their feet so as to reveal what they hide of their adornment. And all of you beg Allaah to forgive you all, O believers, that you may be successful”
[al-Noor 24:30-31]
The suitor is not one of these, rather he is only permitted to look for the purpose of proposing marriage, and the woman does not have the right to adorn herself for him. 
Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) said: It is permissible for the suitor to see the woman to whom he is proposing marriage, but that is subject to certain conditions: 
1 – That he needs to see her. If there is no need then the basic principle is that a man should not look at a woman who is a non-mahram to him, because Allaah says (interpretation of the meaning): “Tell the believing men to lower their gaze (from looking at forbidden things)” [al-Noor 24:30]. 
2 – He should have made up his mind that he wants to propose. If he is still hesitant then he should not look, but if he has made up his mind then he may look, then he should either go ahead or give up the idea. 
3 – This looking should be without being alone with her, i.e. it is essential that she have one of her mahrams with her, either her father, brother, paternal uncle or maternal uncle. That is because being alone with a non-mahram woman is haraam, because the Prophet (peace and blessings of Allaah be upon him) said: “No man should be alone with a woman without a mahram being present.” And he (peace and blessings of Allaah be upon him) said: “Beware of entering upon women.” They said: O Messenger of Allaah, what about the in-law? He said: “The in-law is death.” 
4 – He should think it most likely that she and her family will accept. If he does not think that is most likely, then there is no point in looking in this case, because his proposal will not be accepted, whether he looks at her or not. 
Some scholars stipulated that his desire should not be provoked when looking, and that his aim should be only to find out. If his desire is provoked then he must stop looking, because before the marriage contract is done with a woman, it is not appropriate to enjoy looking at her, so he must refrain. In this situation the woman must come out to the suitor looking ordinary; she should not come out wearing beautiful clothes or makeup, because she is not yet his wife. Moreover, if she comes to him looking beautiful and wearing her best clothes, then he may propose because he was dazzled by her the first time he looked at her, then he will find out that she is not as she appeared to him at first.  
End quote from Fataawa Noor ‘ala al-Darb
Elsewhere he (may Allaah have mercy on him) indicated that this may have the opposite effect, because if he looks at her when she is wearing makeup and fine clothes, he may see her as more beautiful than she really is, and in that case when he enters upon her following the wedding and sees her as she really is, he may be put off her and no longer interested in her. 
To sum up: If a suitor comes to a woman it is permissible for her to uncover her face and hands and head and that which usually appears, according to the correct view, but without wearing any cosmetics or adornments. 
And Allaah knows best.