Foreplay works for me. My bf and I start by kissing, and our hands start to roam each other. Eventually we take each other's clothes off, and continue to roam each other's body. I give him a handjob, and he fingers me and rubs my clit. This goes on for a while, then we eventually have sex. Just try to relax, and enjoy it.

Are you self conscious about your body? Some women get concerned about how their body looks when with a man and that is reason why they can't relax.

You could try using some store bought lube too.
But definetly lots of foreplay

Find some nice relaxing music. That helps. Love is more important than sex.

My wife had the same problem. It is low libido. Take Sentia pills or another healthy supplement to increase your sex drive.