Hello mitch,arsh,
important is a good isolation between the core and all windings.
Use a very good isolating bobbin, isolating foil between every layer of primary winding and also every layer between the secundary winding, 2 x isolation foil at the end of the primary winding and the secondary winding, one layer of protective winding between primary and secundary winding and at the end 2 x isolations foil.
Take care, that the core and the protective winding have very good connection to ground.
I hope it helps
Regards
Rainer