What should I charge? Would it be a mistake to tell her "since I'm new to the CAKE thing I make you a good deal..." Or should I be confident and just charge like I would charge for cupcakes?
You really shouldn't be selling a fondant covered cake until you know how to work with it.
Customers are not for practicing on, it is not fair to them, and can very easily hurt your reputation!
I know that's not what you want to hear, sorry, but it's the truth.
If you are going to sell her the cake anyway, then you need to figure out your pricing structure. Figure out what the ingredients, supplies, utilities, licensing, advertising, insurance etc, will cost you to make the cake. Then you add on a wage for yourself. I can't really advise on a discount, but tell her you are still learning, because chances are you will be giving her a less than perfect cake. If she is expecting perfection and doesn't get it, you will have an upset, disappointed lady on your hands.
Better to be honest with yourself and your client beforehand, than to refund and apologize later.
If you're more comfortable with doing bc with fondant decorations, why don't you just tell her that and quote her a bc with fondant accents cake? If she is dead set on a cake covered in fondant, then she would just have to go elsewhere. But you could at least offer.
I agree with scrumdiddly, don't try out your fondant covering skills on a customer. There are a lot of cakers who just don't do fondant covered cakes at all, and they do plenty of business. So you could just do bc cakes until you have had a chance to practice fondant and feel confident in it.
I know a local baker who sucks at BC and only does fondant. Don't offer what you are unsure that u can produce. Keep practicing until you are good then offer it.