Is not having a plan, a plan? I think it can be. I happen to be a non-planner - or at least not a very good one. Kind of last minute, and I tend to miss a few of the details. I like to think that the creative part of me trumps the organizational part - or lack thereof, depending on how you look at it.
When I need a plan, I take out my "list of plans" and pick one:
1) Off the Cuff
2) A Wing and a Prayer
3) Flying by the Seat of My Pants
4) Off the Top of My Head
5) Winging It
6) Make it Up as I Go.
7) Footloose and Fancy Free
8) Google on the Go
With any of these plans, it helps to carry the mantra that "Everything Will Be Alright"...the Don't worry, be happy concept. If you go by that philosophy, you save yourself the worry of having no plan.
If you pick and accept (that part is important) that any of the above plans will come to fruition with your particular project - then, almost always....everything WILL be alright! And, if not, you can pull out another good plan which is:
9) At some point you quit trying to make the right decision and make the decision right.