How can those infected with HCV prevent spreading HCV to others?

Condoms. Hepatitis c is transmitted through blood and sexual intercourse. Use a condom when you have sex, don't share shaving supplies or toothbrushes, and avoid contact with open wounds.
Avoid blood exposure. Hcv transmitted primarily through blood. Avoid sharing razors etc at home. Obviously no sharing of needles. Hugging, kissing, sharing utencils should be fine.