how would I avoid getting a rash after shaving?

Yeah, there is a way. You can try using hair conditioner. I have tried it myself and its amazing how soft your hair gets, even after a first try. There are various conditioners that you might use, the best thing is to ask some girls about it. But in general you just wash your hair with a regular shampoo and rinse with water. Then you apply skin conditioner and wait couple of minutes and then rinse again. Its amazing how soft your hair gets.

As for shaving it could be because of the shaving cream. Try changing that, or even change aftershave and see how that works. That rash is one of the reasons I do not shave, I just trim my beard with this little machine and it looks just fine. Maybe you should consider doing the same. Hope this helps