I recommended to one of my students not to do these things or if she does to be careful. Many of my students seem to be exposed to these things. Any book recommendations will help. I read a lot of Catholic books.
Superstition means ascribing to a creature powers it possesses neither by nature nor by grace.
Contacting the dead through mediums, ouija boards, etc. is of itself seriously sinful. Invoking the devil is seriously sinful. Astrology is irrational and hence at least venially sinful. The same may be said of ascribing non-existent virtues to crystals. Ditto for chain letters and similar efforts to get something for nothing or to escape the limitations set upon us by our human natures.