Aside from knowing the symptoms and telling the person affected that you're there for them, here are some other ways that you can show support:
Recommend Helpful Resources
If your loved one has just recently been diagnosed it's important for them to have some resources available to them.
Providing them with the resources that have helped you is not only an excellent way to show support, but it also shows how much you care about them because you've done research.
Join a Class Together
Classes and activities are great ways to battle depression; it doesn't have to be a fitness class, as creative outlets are also helpful.
Signing up together makes it more fun and provides you with an opportunity to get them engaged in something new.
Get Out of the House
Those suffering from depression often don't have the energy or motivation to leave the house. Offering to go for a walk, even just around the block can help to lift someone's spirits.
If they're up for it, take them out for coffee or a meal; they'll enjoy spending time with you, and it will break up their routine.
Depression is a hard battle; some are affected a lot more than others, and it can take a while before they find a treatment that works for them. It can be frustrating to see your loved one suffering, but it's important that you continuously remind them of your support and don't give up on them.
Chances are they are already pretty hard to themselves, so you need to step in with positive words and gentle reminders that they are loved.
Depression affects everybody differently, and they may have some good days, and then all of a sudden have a bad one. Don't criticize them for that; just continue showing your love and support and remind them that even though it probably doesn't feel like it, the bad day(s) will pass.