For me getting up 1 to 2 hours earlier than needed was a revolution. Before I'd be in bed but awake into the early hours, shifting the day to get up extra early meant those "spare hours" become productive hours early in the morning. It also means once dinner is finished the evening is my own. I have more time for hobbies, projects, DIY than ever before.
I try and meal plan for the week on a Sunday pm and go get groceries on a Monday for the entire week (I will pick up extra fresh ingredients on Thursday but I do try and plan round the need to go to the supermarket!)
Keeping a notebook with me always, it has its own pocket in my bag, has really increased productivity and relieved stress too! Anything I might need to remember gets written down and then I don't have to worry about "what did I do with xyz?" (Like the other day when I was putting a photo into a little booklet thing, I had put it in a heavy book to keep it pressed, could I remember which book? No. But I'd written it down so what might've been a search even for five minutes through all the big books on the shelf meant I went straight to it!)
An organiser insert or just a multi-pocketed purse is another way I've found saves me time. I'm the biggest scatter brain usually (I am the person who will tear the house apart looking for my phone while it is In. My. Hand.) But now everything has a pocket and I can lay my hands on what I need when I need it. Heck I've even got one outside elastic pocket that I use for rubbish like wrappers or used tissues!
I keep a note holder on my car keys, that way I don't have to find an ATM in the middle of nowhere.
I can't think of anything else, other than preparing for any eventuality! So I've always got painkillers, plasters, tissues, sweets, a spare hair brush, spare make up for touch ups, water, kids activities to keep them occupied, breath freshener, pens, perfume, antiperspirant, spare tights, alcohol handgel, earphones.