I have a female friend and I wish to get married to her. However I am not ready now. Is it permissible to tell her and avoid all acts of sex till we are Islamicly married to each other, if Allah wills? Please, I need a comprehensive reply for I don't know what to do.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

Allaah Says (what means : {Tell the believing men to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts, etc.). That is purer for them. Verily, Allaah is All-Aware of what they do.  And tell the believing women to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts, etc.)…} [Quran 24:30-31]

The Islamic Sharee'ah does not allow looking at non-Mahram women except for a dire need as this prohibition is beneficial for the Muslim in this Life and in the Hereafter.

However, it is permitted in the Sharee'ah to look at a woman if one wants to marry her in the presence of one of her Mahaarim [plural of Mahram -unmarriageable relative].  If he likes her [is pleased with her] and he decides to marry her, then he has to ask her guardians to marry her.  Nonetheless, he should be careful of the devil dragging him step by step to unpleasant consequences, as it is not permissible to be in seclusion with the fiancee  before completing the marriage contract. However, it is not compulsory that you inform her yourself about your intention to marry her; rather, her family may inform her or that you may send to her your famale relatives and female Mahaarim.

Nonetheless, we would like to draw your attention to give importance to the religiousness of the woman while choosing a wife.  The Prophet said: "A woman is married for four things, i.e., her wealth, her family status, her beauty and her religion.  So you should marry the religious woman (otherwise) you will be a loser." [Al-Bukhari and Muslim]

Finally, it is permitted to propose to a woman whom one wants to marry in the future even if he is not ready to marry her at present.

Allah Knows best.