I'm still a bit ADD even as an adult. I manage the problem better now than when I was younger.
Understanding ADD and the long-range view of maturity helps.
Although I can be distracted easily and have many things going on at one time, the other side of ADD is the ability to focus intently when interested in something.
Take this plus a creative "mandate" and you've got someone who goes into a bubble where time, hunger, sleep become irrelevant until it burns itself out. I still do go off on tangents.
I can also multi-task like crazy.
But this can have a bad side too. I can accumulate so many things on my plate, things can become muddled or overpowering. The Coulda', Shoulda', Woulda' rolls up behind me and sticks like Velcro until I become paralyzed. That's when I just have to take a deep breath and either sort it out or go do something else for a while.
One strategy is making long lists, writing things down before they evaporate. That and a good calendar with lots of space for notes is a good way to get a handle on things.
My notebooks, of which there are legion, are just a jumble of everything from measurements of rooms, sizes of frames for images to matt, ideas, sketches, projects, floor plans, grocery lists, interesting recipes, passing thoughts and observations, books to buy, remembrances, to-do lists: A regular brain-trust I can't do without. I finally transferred and alphabetized my books-to-look-for list onto my iPhone so that when I happen to be near a used book store (one of my fav haunts) or the library (another) I'll at least make a better stab at what to look for.
For me, it still has to be on paper. I don't trust electronic storage because too many things can hamper getting to it. Paper. Pencil/Pen. Handy. Simple.