WIP limits are not important to me.

I use my Trello boards for mental hygiene.

Something comes in, I put it on the board to get it out of my head. Then, when appropriate, I go to the board, rearrange the top 5 or so items by priority, then start on the top item.

Many things never get done, but they have turned out to lower priority, by definition.

If I am waiting for something to happen on a current task, I put it second or third in the queue.

Keeps me sane....