Get her used to touching. When you're conversing with her, give her a few short touches on the arm as you're making verbal points to her. I was actually experimenting with that to great effect today.
I went to Starbucks with two young ladies from church who wanted my advice on certain things. I decided to practice, so I started to give them gestures of touching every once in a while. It was definitely outside my comfort zone and I didn't know how they would react.
Lo and behold, they started touching me on their own more and more. It was a doorway to rapport and they loved it.
Occasional touching demonstrates a lot to a woman. Most men are scared you-know-whatless to touch them, so it makes you stand out.
If you get her used to touching, hand-holding will be a natural progression and will feel right to her. Women respond well to what they
think are natural progressions, even when we sly dogs manufacture them.
Also, you can take her to a place where there are rocks to climb on, perhaps the seashore if you're on the coast or some other natural place. You can then extend your hand to help her and she will gladly accept it.
Of course, all of the above are baby steps in order to help you along. In fact, the best move is the bold move of taking her hand just because you want to take her hand, but there is nothing wrong with being unsure and feeling your way through with those baby steps. Eventually you will be in such command of your situations that you will just boldly take her hand when the time is right for you. Not all will agree, but I'm a believer in baby steps to help conquer fear.