Romans 12:9-10 (KJV)

9. Let love be without dissimulation. Abhor that which is evil; cleave to that which is good.
10. Be kindly affectioned one to another with brotherly love; in honour preferring one another;

We come to the portion of Romans that contains some practical exhortations on how we are to live in light of who we are. Behavior is always secondary to beliefs for this reason:

Do you want your life to be particularly rewarding or fulfilling? Love without hypocrisy. This love is patient, kind, without envy, is not self-seeking or easily angered and keeps no record of wrongs. This love protects, trusts, hopes, perseveres and never fails (I Corinthians 13).

1. Show it in your actions and say it in your words.
   "People often profess their love, even to those whom they not only treat with neglect, but in reality renounce and despise" John Calvin.
   1. Showing this love is best seen through the covering of another's sins.
      "Above all things, have fervent love among yourselves; for love covers the multitude of sins" (I Peter 4:8). This kind of love allows people to fail.
   2. Showing this love is fueled by God's forgiveness of your own sins.
      "And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you" (Ephesians 4:32).
2. Hate that which is destructive and cling to that which edifies.
   "Aabhor that which is evil; cleave to that which is good" (v.9). I am of the opinion that this couplet is not to be taken out of its context. Paul is not speaking of a general principle of evil or even a general principle of good, but principles of relationship! "Love thinketh no evil" (I Corinthians 13:5). I filter all I do for those I love through the lens of "Wwill this build up the person I love?" I must actively cling to those things.
3. Display your love for Christ through your love for His children.
   "Be kindly affectioned one to another with brotherly love" (v.11). All Christians are brothers. We are born of God. He is our Father. To love Him is to love His children. "Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth him that begat loveth him also that is begotten of him" (I John 5:1).
4. Lead out in deference to the ones you love, seeing them as better.
   ". . . in honor preferring one another" (v.10).
   The word "prefer" in this verse literally means "to lead out" or "to set the example." When I am loving my wife I am leading out (not waiting for her to do it for me), and showing preference to her tastes, desires, wishes and concerns. It doesn't mean you will always agree, but in honor of the one you love, you value the ideas and wisdom your spouse gives. This is done when you "esteem the other as better" (Philippians 2:3).