The love is the riped fruit of surrender of individual identity.. that means when a person gets totally devoted to either God or Guru is then the love emerges. It is said that culmination of Bhava Bhakti and culmination of Bhakti is Love or PREM. When this state is achieved you will love every one. Till them you have to just practice to love others.
To make this practice effective and progressive - you need to have some rationale to make your mind accept. If you believe that entire creation is due to God and everything is made of God them each of us are some form of God. So, if you prejudice with someone, you actually are prejudiced with God. But you don't want to be prejudiced with God. Thus, love everyone.
There is yet another technique to develop love towards everyone is to believe that every living entity in the universe behaves according to their destiny or PRARABDHA. It is the nature that makes everyone do karma, not the individual himself or herself. So, if they are not the doer why should have prejudice or hatred with them? They simply the means. If someone abuses you or beats you - it is the nature who is doing it not that person. You should not have any negative thoughts about that person. You should be angry on nature. Since Nature is God, you should be angry on God. With practice of this technique you can develop love towards others.
