Hi,
I live near Dewsbury and my sister is currently living in Dewsbury (her house is up for sale) its not a bad area that she lives in but also not the best of areas, they have never had any trouble. I would recommend looking at Cleckheaton, Mirfield, Liversedge, nice places, some nice houses and not too expensive. I would avoid Heckmondwike, although I have never lived there I have heard not so nice things about it, although saying that bad things were said about the place I grew up in but it wasn't all that bad. The best thing I think is for you to have a drive around the area, you will get a feel for places and what they are like. Good luck!