The simplest answer is this -- assume the viewpoint of God: Love.
If our love is unconditional, infinite and generous, then forgiveness becomes easy. If we still cling to something as "important," then our love becomes impure. If someone steals our money and we remain attached to that money as "Important," then we cannot forgive. We must view the money as decidedly unimportant and love to be of utmost importance -- important not to "self" (ego), but because it is what the Father is.
Another approach to forgiveness is one of taking perfect (100%) responsibility for the actions of another. Most people are hardwired to blame someone else for the things those people have done to us. Blame and responsibility are polar opposites in this mortal realm; but True responsibility in its perfected form is divine -- above the dichotomy of responsibility-blame. This perfect form of responsibility has no blame -- not even a spot of it. If you take 100% responsibility for anything, you can no longer be a victim. Thus, turning the other cheek (forgiveness) becomes effortless.
Still another approach involves faith -- the perfection of confidence. But with this, you also need utter humility, because without humility, confidence becomes arrogance and forgiveness becomes impossible. With humility and confidence, one fearlessly accepts that which is given with humility. Thus forgiveness becomes effortless.
Finally, if we are perfectly grateful for the gift someone has given us, no matter how evil it seems, then we are assuming the viewpoint of the Heavenly Father and are walking with Him once again.
Rod Martin, Jr.
"The Art of Forgiveness"