This verse is probably one of the hardest teachings of the Christian faith for people to accept. Most people have an inner moral compass that guides their sense of right and wrong. When the line drawn by that compass is crossed, it is hard to forget and forgive, especially if there was malicious intent. There is a way to make following this command easier.
Be mindful of your humanity and the humanity of others. Keeping the veil of our mortal fragility on helps us treat people with love. No one person is perfect and we all make mistakes. We are all at different levels of maturity, knowledge and wisdom. Therefore we all stand in need of grace in some form. It is okay to disagree, just do so with love as the intent. Everyone will not like you and you will not like everyone. That's okay too, just be respectful and courteous in your limited interaction. So go ahead and make the effort to love your enemies. You might even turn their heart towards you and become cordial acquaintances. Remember, when the light of God's love shines through you, others respond to it. But if people are not responding to the love you project, what are they responding to? The vibe you send out will come back to you so make sure it is the love you want extended to you.