I don't really have an answer to that question, I don't have '7 Easy Steps to Loving Everyone All the Time' and I don't think anyone else has figured it out. But I do know someone who did it perfectly: Jesus. Jesus came for the broken, the lost and the needy. He came for you and he came for me. Jesus loved the unloveable.
Throughout the New Testament we see countless examples of Jesus hanging out with the lowest of the low. He consorts with tax collectors (a big 'no-no' for Jews), prostitutes, the sick, demon-possessed and every low life around. And what did he do? Tell them to, "Begone, wretched sinner!" No, he loved them, healed them and set them free to love others in return.
I'll be honest, a lot of the people Jesus spent time with would make me uncomfortable. I have a hard enough time loving those closest to me, let alone the rejected and forgotten. What makes it so hard? Are we really all that different? Not in God's eyes:
"For all have sinned and fallen short of the glory of God" (Romans 3: 23)
And for those of us redeemed by grace there's certainly not some hierarchy of Christians! I am not more holy or righteous than any other Child of God:
"There is neither Jew nor Gentile, neither slave nor free, nor is there male and female, for you are all one in Christ Jesus." (Galatians 3: 28)
So we're all in the same boat: needing Jesus to set us free and then attaining equality of status in the kingdom of God. However while this can help change our perspective it doesn't give an easy, quick-fix solution to loving the unloveable. Jesus had the advantage of being, well, the Son of God and free from sin. But we too are set free through Jesus' death and resurrection. That doesn't make us perfect, we're still going to stumble, still going to get angry at people and reach a point where loving them is the last thing on our minds (the nearest heavy object and assessing our throwing ability is more immediate)... But no matter how hard it gets remember that Jesus loved the unloveable and instructs his disciples to do the same: