It looks like you may have 3 issues that are important for Kanban -
- You have a high WIP issue.
- You may have a prioritization challenge.
- You also have a 'sizing' problem.
Let me elaborate on each -
High WIP. Clearly, you have a number of well-defined and not so well-defined projects that you have to do. The projects seem sizeable enough to manage on a Kanban board. So, like Aymeric suggested, you need a "Backlog" (waiting list) area prior to your "Ready" column - where you should keep your 'just ideas only" projects - so you don't lose sight of them - but don't move them to the Ready or In-Progress lane before they have been reasonably well-defined.
For the well-defined projects - like prepping you car for sale, you may want to break them down to smaller tasks that you can better see progress on. A single "prepare car" project might take days or weeks, but smaller cards like "get smog check", "Detailing the car", "get new tires", etc. will be shorter - and you will be better able to get a sense of progress, better define your project for your own clarity - and better sequence/ prioritize individual tasks. Dealing with tasks at this level also might help reduce procrastination!
Most importantly, breaking down projects to more 'equal sized' tasks across different projects will give you a clear picture of really how much work you are dealing with - and thus force you to start only one (or a fewer) things at a time, work on those with the highest priority AND complete them before starting others. Kanban is all about "Stop Starting, Start Finishing!" as you probably well know :-)
Second - Prioritization is key - and certainly not easy. Hopefully, the above approach helps you do it better. Also, it helps to not try prioritize everything you have on your plate - just the top 3 or 5 things - and MAKE SURE you finish them before starting on something new. If something more important DOES come along, it is important to move one of the In-Progress items back to the Ready or even the Backlog column - so there is no clutter on your KB.
Third - Sizing - The project breakdown to tasks of course helps sizing. The other thing is the really small stuff that doesn't even make it to the KB. It would help to keep aside some time for these tasks - and be clear that for the tasks on the KB, you only have the remaining time in your typical day. So, if you think you need 3 of your 8 hour day for the small tasks, keep 4 or 5 hours only for the KB tasks. Again, this helps you better understand what your real capacity is and so what your throughput can be. Most of us are guilty of believing that we have more time at hand than we really do.
And I agree with you and Aymeric - that for repetitive tasks, Kanban really does not serve the purpose.
Hope this helps. You didn't say what tool you are using for Kanban - but if you need one, you can take a look at SwiftKanban (http://www.swiftkanban.com) - it has a free version that you can use for up to 10 boards/ 20 users (so you can get others in your friends and family circle involved as well) PLUS it gives you some of the key Kanban metrics to track your performance!