Propanolol - game-changer for managing anxiety.
Therapy - a lot, with a very good counsellor. Both for unpacking a lot of what was at the core of the way I felt, and for learning ways to manage my emotions; also learning to really understand that I am not my feelings or emotions. Knowing myself.
Getting enough sleep. Making my bed, and bedroom, a good and safe place to be. I've also got a small stash of melatonin for when I need some help with dropping off.
Movement. Exercise I like - for me, weightlifting and yoga, with the occasional dance class. Getting outside for long walks. When I'm feeling the mood coming on, doing something - anything - around the house like the dishes or hoovering, to get out of my brain and into my body. Not spending time on my phone. Doing sensory things (agree with the comment about perfume above - I have loads of samples!)
Spending time with people I love and care for, and who love and care for me, especially if we're just hanging out or doing fun silly stuff. Even just texting with folks is good. When I feel a black mood coming on, all I want to do is hide myself away and actually it's far better to be around people then - it's taken a very long time to to put that into action.
On the other side - having a handle on the people/places/etc that will bring my mood down. Setting boundaries. Learning to say no.
Eating well. Staying hydrated.
One of the most useful books I've read recently which has helped was 'Know Your Self Worth' by Anna Mathur. Most of what I've described above comes down to treating myself with worth, as someone worthy of love, respect and care. Depression tells you otherwise, but you are worth the world and should treat yourself gently and with love.