how to lose virginity with less pain

First, the woman must be very aroused....that means WET, from her arousal. 

Second, if she's not wet naturally, then you both should use something like water-based personal lubricant so that you glide into her.

Third, she might have a tough hymen. That means it's not likely to tear.  This is easily dealt with in a doctor's office on an out-patient basis.

Fourth, if she's not real relaxed about this, it could be vagimitis.. which is the involuntary "clinching" of the vagina to prevent penetration.  That also would require some counseling and practice to over-come.

But all of this is very do-able.  Start with the check list, and if she's still willing, you may want to go together to visit a doctor to describe your difficulty.

Good luck.

PS: You both might try reading a really good book on the subject of sex:

The Guide to Getting It On, by Paul Joannides

Everything you Always Wanted to Know About Sex by Dr. David Rubin