1- Exercise - I generally think that walking or running on trails in nature is one of those generally free beneficial thinks you can do for depression. Worse case scenario, you improve your fitness and feel better about the shape of your body.
2- Sleep - Yeah, this is a massive one, aim for at least 7-8 hrs. Regular exercise will help, but try to keep a relatively even sleep schedule (schedule yourself to be in bed without your phone by 10pm is a lazy but easy way to help).
3- Limit doomscrolling - Looking at the latest news about what craziness is happening in world probably isn't that amazing to do that often, so limit it a bit.
4- Diet - I'm vegetarian, and when I started years ago I noticed it really seemed to make my bouts of depression easier to handle. That being said, at the very least make sure you aren't eating too much junk food and try not to drink. If you aren't getting enough of a particular nutrient, take a multivitamin (magnesium is a pretty common deficit for most, and can affect your sleep).
5- Meditation - The act of breathing can occasionally give a bit of a break from the spiral of depressed thoughts, so it's no wonder that a lot of therapists tend to recommend it. Just start with 10 min a day and see if that helps any.
6 - Atmosphere - I know his can't always be helped, but just adjusting your living environment can make a tremendous difference. Try taking a day or so just to thoroughly clean your room/apt/house. Personally, my advice is to clean like you are trying to truly help someone you love/respect so that at the end you feel like no stone was left unturned.
7- Music - Kinda try to find some music you like that is soothing and try to like, and limit depressive or harsh music. Sounds stupid, but it helps some.
8- Psychedelics - A bit controversial, but I personally use shrooms long term to handle depression. They honestly have been the best long term depression maintenance I've found for the price. But truthfully, most of what they do is give you a few hours to step out of your emotions, and force you to actually look at yourself. They are basically just making you acknowledge the above for the most part, and after a trip if you don't make changes, they won't really help that much. Pro tip, a notebook to capture your stream of thought can be very helpful for post trip integrations.