I don't know about you, but I'm kind of addicted to pretty notebooks.
My dad used to say (in fact, he still does) that I must have been a pencil or a pen in a former life, I like paper so much.
I have stacks and stacks of pretty notebooks in all sorts of sizes and colours and designs, some lined, some blank (not a fan of squared - too regimented for my pantser tastes). Now, there's nothing wrong with having notebooks, of course... but...well...
I have this tendency to start writing in my new favourite and then abandoning it for another, or having this bright idea of having one notebook for each of my endless array of plot bunnies, or any other variant of that writerly boogeyman, procrastination. Because all that occupation with the notebook stops me from doing what I should be doing: Buying some superglue and sticking myself to my desk chair so I actually have to sit there and WRITE.
Yes, that's right. WRITE. Because my writing has been sporadic (at best) the past few month, and this is not something I can recommend.
So don't do what I do. Don't get preoccupied with the shiny new notebook (or, Muse save you, trying to find the PERFECT notebook), don't bother trying to find the perfect word processing software, don't worry about whether your pen is blue or black or pink or just a pencil stub.
Because the basic recipe for being a writer?
Pen/Keyboard + Paper/Computer + Imagination + Butt-in-seat, and it's the last two that are most important.
The rest is just window dressing.