You want to ensure that the information presented is current, so look at dates of when the content was written or posted. Try to find out who is funding the site, is it funded by a company selling something they are advertising, is it funded by donations, is there any chance the information is biased based on who is funding the site? Finally you want to search out the privacy policy, if you are giving personal information is the site protecting your information? Web site information can always be helpful but it should never replace the medical opinion of your doctor, so please seek guidance from you doctor when needed.
Some quality websites you can visit are:
Alzheimer’s Association www.alz.org
American Cancer Association www.cancer.org
American Diabetes Association www.diabetes.org
American Heart Association www.heart.org
Center for Disease Control and Prevention www.cdc.gov
KidsHealth www.kidshealth.org
Mentalhealth.gov www.mentalhealth.gov
Reference:
Medline Plus. (2015). MedlinePlus guide to healthy web surfing. Retrieved from https://medlineplus.gov/healthywebsurfing.html