it's not that SH are difficult, but they have a set of very specific needs. if these needs are met, one can keep them successfully.
some of the best tips i can offer are:
keep them cool. even tropical species should be kept <74*F.
don't cramp them. a standard 29 gal is perfect for a pair of larger species SH.
shy away from "plug n play" systems like the nano cubes, aquapods, etc. these systems all run too warm and require modding to be good SH setups. i own 4 PnP's but none are used for SH.
buy true captive bred (CB) SH, and obtain them from a reputable breeder or hobbyist-breeder. these SH will come to you eating frozen mysis and will be free of disease/parasites. don't be fooled by the "bargain" "tank-raised" specimens most LFS carry. SH ship very well, so don't worry about that issue.
HTH