I cannot marry now because the circumstances are not ready. I do not want to fall into a sin but it is becoming very difficult to control myself. What should I do? I need your help.
[ Related Quesiton ]
As you know one of the aims of marriage is to gratify the sexual needs and instincts and there are other purposes also for marriage which have been enumerated and explained in their appropriate places. Although it has become relatively difficult for many people to marry, those who adhere to Islamic manners and etiquettes and believe that all problems are solved with God's help they can, with reliance on God, follow the Imams' tradition and lifestyle and can start their marital lives by holding a simple and effortless ceremony. If they do so, God has promised to enable them out of His own grace as the Quran says: "Marry those among you who are single, or the virtuous ones among yourselves, male or female: if they are in poverty, Allah will give them means out of His grace: for Allah encompasseth all, and he knoweth all things." 
Thus, the best way that is proposed to the youths so as not to fall into a sin is to take marriage easy. If an individual expects to have all means of livelihood and the best income before holding a wedding ceremony, he must know that such a thing has not been and is not possible for ordinary people in society. In the past, in fact, the youths used to take action for marriage after attaining physical and mental maturity. Thereupon, they would start working hard, toiling, getting busy doing a job and then having a house and stable income.
Hence, therefore, you can try to take action for a simple and frugal marriage at your earliest convenience and as soon as you can so as to guard yourself against sins. You must know that if you adjust some of your expectations and requirements in regard to a girl whom you would like to choose as a life-partner and if you marry a girl who is financially in a lower position than you, you can find many good girls to choose for marriage; otherwise you should restrain yourself from falling into sins. If you fail to marry, fasting, studying, taking exercise and thinking about your own personality as a respected human being can help you stay away from sexual sins. Surely, you should also stay away from sexually exciting and provocative things or going to such places where you might be excited sexually.