Basically, Val's normals are complete shit (much too slow and don't control much space), and she doesn't have something like Gregor that she can use to totally turn the tide and go on the offensive while on heavy defense, so she kinda has to run away and hope you blunder into her. Just don't try to chase her when she does this. Countercall her assists, and don't chase her when she's sitting somewhere that you can't get to -- she can't do anything to you from there, either.
If she decides to go on the offensive, she's just a shitty version of Filia or Fortune. Her lack of any frame advantage except for on her jabs and her multi-hit s.mp (which is easily pushblocked) means she has no block pressure at all, so you only have to guess right on one mixup, and then she's back to neutral (or getting hit).