I change productivity tools from time to time. Here's a latest try.
There are only two real rules with Personal Kanban: 1. Visualize your work 2. Limit your work-in-progress
I wrote about Personal Kanban before back in 2010, but I didn't try to put it into practice as such.
Boardthing is an invention of Dave Gray. There's a review of Boardthing from Chuck Frey which goes into a few more details, but the short summary of it is that it's a suitable way to rearrange little rectangles on a board. The little rectangles each have some text or an image in them, and they can be nested so you can move them around in groups. There's really not much more than that, and it runs in a browser.
This infrastructure is enough to create a Personal Kanban board. Create little rectangles at minimum for "Things to do", "Doing", and "Done", and type into the little rectangles to move them around until you figure out what to do, stop typing, and get something done. I recommend a "Things not to do" rectangle as an added productivity boost.
How does this work in the long term? The system is pretty light weight, and it saves your state between sessions. I suppose if your page gets too cluttered you can start a new one that is more focused. Having a smallish screen forces you to limit your work in progress, which is a good thing.
Dave Gray and Jim Benson have a set of approaches that should work well together, this is mostly written for the both of them as an introduction of sorts.