Burning sensation during vaginal masturbation

It really sounds like lubrication might be the key here. Also, you could try a vibrator.

You will never do it, until she knows how she wants it. she needs to masturbate and find where it feels good, and how she likes it. Only then can she tell you how and what to do.

If the burning sensation is where you are fingering her, then it may be that you are rubbing her raw. Even if friction isn't the problem, over-stimulation may be. If the nerve endings get overly stimulated it can feel like a burning sensation. Think about plunging your hand in ice water.

The burning sensation can also be caused by engorgement of the lips and clitoris. It can be a matter of how her brain interprets the feedback from her body.

Don't concentrate only on the spots that feel the 'strongest'. The entire body is an erogenous zone and the most important part is her brain. If it isn't involved, then she probably won't orgasm no matter what you try. Keep it from being distracted by varying your touch-the pressure, tempo, where you touch, etc. You can also share fantasies or ideas. If all she is doing is giving you step by step instructions, then she may be thinking more about communicating than letting the feedback between brain and body build up. It's a fine line between letting you know what feels good and enjoying the feelings. As you become more experienced with each other, it will get better.

You may think your hands are clean but make certain that you aren't touching anything that she might be having a reaction to such as certain lubricants, latex, rubber, soap, perfume/cologne/body sprays, etc. Some women have stronger reactions to common substances when they come into contact with their genitalia than they do touching them in other ways.

Be patient and don't try to rush anything. Many women have problems reaching orgasm so she is not abnormal and it isn't you.

Chuck is correct that she needs to know how and what arouses her to the point of climax. What I have told you goes for her too when she masturbates. Get the brain involved and good luck.