I've been playing around with this myself. I use Evernote for managing my actions (based upon GTD methodology), and find the tag structure works very well if you keep it organized. I also try and limit the number of workbooks as well. For my personal life, I have two main notebook stacks. The first is for my Active Actions (things on my "to-do" list in various contexts). The second is for reference materials (including Completed Actions). The two notebook stacks with notebooks are laid out as follows: Active Actions (stack):!Inbox@Agendas@Calls@Checklists@Computer (Internet)@Errands@Home@Plans@Someday@Waiting For@Work (if you manage work related items here as well)Reference (stack):@Completed ActionsReading Items (unread)Reference MaterialsI find I really don't need much more structure than that. I have a few other workbooks for very specific things where it's easy to track and sort those items, but I really try and limit those. With that organization of notebooks, I use the tags to provide some structure to what all has my attention in life. I started by looking at how I had organized files on my PC, and then just took a basic inventory of everything else in my life that I dealt with on a fairly regular basis. The first section is a list of tags that represents all my projects that I'm working on (there is a plan for each of these in my @Plans notebook). The second grouping is tags for my reference files (but may also be used on certain action notes as well). In order to prevent over-proliferation of tags (which can easily happen), I have one cardinal rule - I never create new tags ad-hoc. My tags are managed in a hierarchy that reflects things that I do or have an interest in anywhere in my life. I then do a quick review of these on a weekly basis (for projects) and less frequently for reference tags. But here's roughly how the tags are structured: . Active Projects Home Projects:PH/Decorating my home officePH/Plan Christmas VacationPH/Writing Project 1PH/Project APH/Project BWork Projects:PW/Project XPW/Project YPW/Project Z.Inactive Projects (I move completed projects to under this subheading and keep it collapsed and out of view) Note that all my project tags begin with "PH/..." for home projects, and "PW/..." for work projects. This allows me to quickly see my project lists when I create a new action (or have a reference document related to a project). If I'm adding an action related to a home project, I just type "PH" and it brings up my whole list of projects so I can tag the appropriate one. Then I have reference tags for everything I do and or care about in life, but that may not be related to a specific project at the current moment. Note that comments in Italics are just commentary, not part of tag title. My tags look like the following: Reference Tags: .Activities (everything that I participate in):CookingCyclingGuitarMeditationReadingBooks (I like to write a little summary of key books and keep them as reference where I can easily find all of them)RunningShoppingSpeakingSwimmingTravelWritingVolunteeringOrganization AOrganization BYoga.Assets (all my major assets for which I track documents, which luckily is not many):SubaruCondoFinancial:Institutions (for ease of tracking correspondence, statements, etc.)Bank ABank BBrokerage 1Brokerage 2Insurance Company XInsurance Company YCondo AssociationExpenses (I use this to keep track of receipts easily once I scan them in - starting with "0X" allows me to easily categorize scanned receipts)01-Unfiled (not yet submitted)02-Filed (submitted and not reimbursed)03-Reimbursed04-Deductible (I'll quickly sort these and give them to my accountant at year's end)05-Non-deductible (but that I need to track for other reasons)Taxes (any tax related documents)Subjects of Interest (I like policy/politics and have other interests on various topics I might later want to easily reference):Campaign FinanceEconomnyEducationEnergyEnvironmentFeminismFoodForeign PolicyG A Y Rights (interestingly, Evernote doesn't let me write out that word)GunsHealth CareLeadershipNational SecurityReligionTechnologyWho (not my whole contact list, but people I interact with regularly, or have commitments to on a regular basis - allows me to easily find things I want to discuss with them or to capture something they might like and later reference it):MomDadSisterNieceNephewFriend 1Friend 2Friend 3etc This list can seem a bit daunting when you first look at it, but I only review it periodically (adding new topics/activities/projects as necessary) and it has structure that reflects how I spend my time in my actual life. It's actually very cathartic to have it all in front of you and realize how you spend your time. And once you get it in place, it's easy to maintain (and to change around if you end up needing to do so). Hope this is helpful.