We have often talked about the importance of sex life and the essence always lies in communication. But there are some other influencing factors:

More frequent sex:  Frequency of sex is one of the strongest predictors of sexual satisfaction; couples who stop having sex often tend to be less satisfied with their sex lives.

Frequent hugs and kisses: Physical intimacy is associated with more satisfying sex. Kisses and hugs after sex also lead to a happier sex life.

Sexual functioning:  Problems with sexual dysfunction, such as pain during sex or difficulty maintaining an erection, lead to lower sexual satisfaction. Unfortunately, sexual dysfunction in one partner tends to have strong effects on sexual satisfaction in both partners.

Happier relationship:  Sex is better when you and your partner generally get along and are satisfied with your relationship.

Better sexual communication:  You and your partner talk openly about your sexual wants and needs. The quality of sexual communication seems to be more important than the frequency of these conversations. Communication appears to help both by creating intimacy and by helping partners meet each other's sexual needs.

Less porn:  Research shows that continued porn leads to lower sexual satisfaction, both for the person watching porn and for their partner. 

Variety:  It's not just the frequency of sex that matters; variety is also important. Couples who experiment with sex report higher sexual satisfaction on average.

Equity in initiating sex:  Sexual satisfaction decreases when one partner always initiates sex. 

Continuous orgasm:  Of course, achieving orgasm is an important element of a satisfying sex life.

Life satisfaction:  Finally, a happy life and a happy sex life tend to go hand in hand. 

If you are not satisfied with your sex life, the data above suggests some possible ways to improve it. For example, communicate more openly with your partner about sex, reduce or eliminate pornography from your life, and add some innovation to the bedroom.