I first experienced dp 2 years ago and yes it was awful as so many know. Now I still have dp, but I normally forget about it. I guess that really just emphasises how much it's in the head, I only remember it when I think about it.
Tip 1: It's OKAY. I know it doesn't feel okay, I know it's scary and you may feel lonely and that it's tough. But it's okay. It may be harder than it sounds but try not to panic. You'll live, and you will be happy, it just takes time to get through this.
Tip 2: Know a bit about depersonalisation first. It's a natural brain defence mechanism. So don't try to fight it, it's not something you can fight. Your brain will stop feeling the need to defend only when you stop panicking and forget about any danger.
Tip 3: However, after you have a bit of research, STOP googling, stop obsessing. Towards the beginning, I went through every site, every blog, every YouTube video to simply find the cure. I know and understand the addiction, but constantly obsessing over it isn't going to help whatsoever. Force yourself to stop.
Tip 4: Distract yourself, this is the only way you're going to forget it. I received this advice from online, and I know and felt how hard it was to do this at the beginning. You ask "how can I not think about something by thinking about not thinking about it?" After all, it was on my mind constantly. But this step takes time. Get off technology, perhaps find your hobbies, enjoy time with your friends, and even though this won't work immediately keep yourself DISTRACTED. It was a week after I first experienced dp when I had a breakthrough (I didn't think about my dp for 5 minutes) and to me that was a blissful accomplishment. There were times when I went backwards, but overall, you forget about it for longer and longer periods, just as long as you don't think about it it pays off.
Tip 5: It's probably good that you tell a close friend, a trusted adult or maybe even a doctor if feel the need. However, after telling someone to let them know how you're feeling, try or maybe ask them not to talk about it often. Also, keep it to a select few supportive friends and family only. In the end, talking about it likely won't help. The aim is to forget it behind. After all, there is no better advice that someone who hasn't been through dp can give than to simply don't think about it.
Tip 6: Be patient. It's unbearable, scary, isolating. Sometimes you might want to scream, slap some reality into yourself, you think you cannot last another day. But you can. If you're new to dp, you might wonder how you're going to survive long enough to recover... You will. Each person is different, but you'll be okay in the end. Deep breaths.