You've probably heard a lot about Obsidian Portal or other Wiki systems to keep track of your campaign. You don't need me to tell you about them as nearly every website or forum is filled with helpful people that will discuss them with you. I don't use these sites anymore, and basically it is because I am too lazy. I am too lazy to learn the wiki code, or to lay out my entire campaign setting on a digital website. What's more, when I did use them my players never bothered with accessing it. They weren't up for doing homework and that is what I felt Obsidian Portal was. Every entry was homework.
Then there is Evernote or One Note. To me, these systems were like shoving clippings into a folder. Yes you could get a lot of ideas into one doc but they always seemed slapdash to me. I'm probably not using these right and I'm sure Your Mileage May Vary.
Believe it or not I just use MSWord. I can feel the hisses from here and I haven't even published this post yet. It's like this, I make my campaign as a living pdf/doc. If oyu know how to use headings in Word, it's awesome. Each Heading becomes a bookmark and you can move everything under a heading to a new location by dragging the bookmark. Not only that but when you export the doc to pdf, the headings instantly become bookmarks making searching your campaign doc just as easy as searching pdf books. I keep making whatever changes I need to the Setting Doc, export the PDF, and load it onto my tablet. If I ever need a hard copy, I have a nicely formatted document as if I was publishing. In fact, if the setting is a winner, I may just publish it.
Elevator PitchI open each doc with a paragraph that describes the gist of the campaign, the concept, and feel of what I want. I might also site some inspirations in case I find myself getting lost on the original concept.
Rules In PlayOn to the nitty-gritty. Rules In Play section lists anything I want to change from the core rules for my world, both in play and in character generation. For instance, one setting I ran for Pathfinder had no half-breeds: Half-elves or Half-Orcs were not permitted as character races. There was also a list of character classes I boycotted for the campaign. All of this info would go in this section.
GearI add any available gear into the document, even if it is also in the core book. The First part of this document can double as a primer for my players so having all the setting equipment in one place is handy.
LocationsI jot down interesting locations as I come up with them, whether or not I have plans for the pcs to go there. If the Players want to steer the their course away from my plans, I'm ready with a few choice locations of interest for them to explore. I'll give the place a name, list a trope if it fits one, and a few Aspects (ala Fate) so that I can keep the description short.
Example: Obsolam - Robot Graveyard. Where the Obsolete go to finish their run. "Praise Be to the Place We Dare Not Go". "Do not disturb our bones, for we are not yet dead".
FactionsWho are the power players and what do they want? Again I just list ideas as they come to me and keep the descriptions short and sweet. I may not use them so I won't waste too much time developing them. Besides, I find that the best details about these factions come out in play a lot easier than trying to write them in a vacuum.
BTW don't edit yourself. It's better to have a bunch of ideas that you think might be garbage in your doc than a single blank page. You can always revisit the bad ideas and make them better.
Example: Lazarus, Inc. - Seeking immortality at any cost. Walking an unspeakable path. Funded by powerful people. "If I can't take it with me then I just won't go".
NPCsIf it's a connection, I'll add a couple of sentences describing their personality, what they do, and where the PCs met them. I build out combat NPCs on my NPC Cards and keep them in a little card file until I need them.
Hint: If you don't like printing my fancy pants NPC cards, buy some index cards. I like to get some 5x7 cards and cut them up into 3x5s. It get 3x5s with portrait orientated lines as opposed to landscapes.
Adventure PitchesJust like Adventure Mondays. I toss in any old idea in one sentence so I can pull it out and run off the cuff whenever I need it.
Invariable the question gets asked on RPG.net or your local game forum what is the best Tablet for reading PDFs. The answer is get what you can afford or what you want for other pursuits. Newer models are going to have more memory and better draw speeds, but a lot of how well a tablet handles pdfs has to do with the software you use to read them.
As for me, I'm running a Nook Tablet HD, which I picked up for $150 at the time. It's not the best tablet and I mainly use it for web surfing, youtube, and reading my PDFs. It was a nightmare for a while but then Nook went Android and I was able to download EBookDroid. It has the fastest response time I have found when switching pages and its free.