The best solution for him is to marry. If it is difficult then he should keep fast as much as possible. It is narrated in Hadith:
یا معشر الشباب! من استطاع منکم الباءة فلیتزوج، فانہ اغض للبصر و احصن للفرج، ومن لم یستطع منکم فعلیہ بالصوم فانہ لہ وجاء (مشکوة: 2/267)
Also, he should resolve to refrain from acts that cause indecent feelings like gazing women, looking at obscene pictures and so on. If he feels tempted to sin he should visualize the punishment of Allah and fatal diseases. Moreover, in case of committing sinful acts he should bind himself to do any difficult task like offering hundred rakat nafl or charity of some amount.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband