Here are a few things I've learned about supporting a loved one with mental health issues:
A person suffering likely can't tell you what they need at the moment. The pain and feelings of isolation and worthlessness feel permanent, and they feel like they're drowning. Just like you wouldn't ask an actual drowning victim how you can help, don't ask a depressed person what you can do. Jump in. DO something. Saying "I'm bringing you by some dinner" is more powerful than saying "can I bring you by some dinner?" Declining help that is offered is much easier than asking for things.
Here are some links and resources to help friends and family of people suffering from depression and other mental health issues. National Alliance on Mental Illness, Help for Friends and Family Members of People with Depression,
There are many resources out there for family members and loved ones of those suffering from mental Heath issues as well. It's important to take care of yourself, too- be sure not to allow caring for another to negatively affect your health.
Jenise Harmon, LISW-S is the founder of New Wings Counseling and a licensed therapist who specializes working with couples and individuals who struggle with depression, anxiety, personality disorders, and general life struggles.