I use old-fashioned paper and pen. Keep a todo list on a page; each day-end I add/subtract and when it gets full, copy it to a new page. This makes me revisit each item, which may create associations to newer tasks that are related.

When I start from neutral, whether at start-of-day or after finishing a task, I check off what's done, then review the list to find a ripe task to launch into.