Tips to stay organised

Hi guys I’ve been feeling like I have a million tabs opened in my brain. Usually it’s not this bad but so many unlucky things happened causing so much stress and costing a lot of money. I’ve been very clumsy lately and forgetting a million things even my friends graduation. Although I’m not that close to her but how could I forgot this when all week I’ve been reminding myself that I have a graduation to go to. But she invited so many people but I still feel like such a bad friend for forgetting but I’ll buy her flowers to make up for it. Am I an asshole? Anyways I also work 2 jobs and do uni full time but I need to work as I need money. What are the tips to stay organised and be collected I’ve just been so down the drain and a million things in my mind.