When you design the statistics for your NPCs and monsters how do you format them, where do you put them, and what medium do you use?

Do you arrange them in tables or as individual block entries? How much space does each entry take up? One monster per page or several? Single or double column?

Do you categorize them alphabetically, by difficulty, by type? Do you scatter them all over your game notes where they are likeliest to be used, or do you keep them all at the back of a campaign binder?

Do you prefer them printed out or hand-written? Do you just leave them on screens now? Do you use full pieces of paper or index cards?

Do you attach illustrations you got from various sources?

Do you leave post it notes in your monster manual that contain notes on re-skinning or minor changes?

I write them in Word, or Excel, save them as a PDF and put them on a tablet PC.

They are normally of the format (For D100/R1/Legend/BRP games):

Name
Short description
Characteristics
Attributes
Hit Points/Location
Skills
Spells
Magic Items/Other Information

Each takes about half a page.

Where they are part of a scenario, I include them at the point in the scenario where they fit best.

I use a standardized form for NPCs in Honor+Intrigue, an MS-Word template* set up with appropriate paragraph styles. The form is 5.5" x 8.5" so that I can print two NPC records on a single letter size page. The record includes an image of the NPC. I have two filing systems. I keep electronic versions of the individual NPC records on my computer. These are filed alphabetically by name in a People folder on my computer. I print the records for NPCs who are likely to show up in play. These are filed in two thick mini-binders. divided by location and several subheadings. Fewer than a third of the NPCs are printed.

I have more information about how I record and store NPCs and examples of several NPC files on my blog.

I've used MS-Word templates for NPCs and PCs since 1995, which includes Call of Cthulhu, Honor+Intrigue, Runequest, Star Trek, and Star Wars. Back in the 1970s and 1980s I used 3x5 index cards for NPCs for D&D and Runequest which I kept in index card boxes organized by location and alphabetically by name.

I've used notebooks, 3x5 cards, and even partially coded a MapTool set of macros to create and store characters.

Currently, I'm exploring TiddlyWiki5 (http://tiddlywiki.com/) - which looks amazing for this sort of thing. It's a full "wiki" in a single page of HTML+javascript, built to be a quick note-taking tool that you can go back to cross-link. Apparently, if you setup a little javascript on your PC, you can serve multiple wikis that all link to each other, and access them from other devices on your network (the method I'm trying to setup this weekend). It even has a plug-in to print 3x5 cards, and one for visual relationship/concept maps of the wiki entries. See http://tiddlymap.org/ for some awesome demos. That was the killer feature for me. I want faction charts! Party to NPC relationship maps for each location! Large scale political conflict maps!

I use word, too, and usually use a template, with mods.

So, when i made a Zinc Golem, I referenced the MM page where Flesh Golem was, then made notes (reduced melee attack, plus big anti-magic spell-retargetting ability). When the players see the monster, I just turn to the MM page, then consult my notes for minor changes.

I don't.  They're either taken whole-hog from a published book, or I make them up in my head and mostly wing it.

New or old I use index cards and jot down what might be in an encounter all on one card, any notes on what they have or were doing that might or might not pertain.

Name: AC, HP, attacks, damage, specials if any, gear if any, stats if its likely to come up, CR and EXP.

Pretty much compressing each entry into 1-3 lines depending on the monster.

The NPC treatment depends on the nature of the NPC. For regular folks and generic monsters, I usually set up a word doc with generic stats, then list NPCs with a name, description, any exceptions to the generic stat block, personalities, and any relevant notes about goals, role in current events, etc.

Important NPCs and monsters get a full stat block along with the notes and descriptions.

Using a word processor I create a Regional Random Table at top, then add monster (or demi/human/oid) stat lines, or anomaly encounter note, beneath.

Most generic NPCs get a work position title and 1 to 2 personality adjectives. This also however includes high social status people, because if you attack them then comes the deluge of institution defending them. In this way I don't have to care about needing high lvl NPCs in positions of power — the system of organized community defends itself.

(No one's going to willingly let pass PCs killing off a group leader, let alone hand them the title. PCs are now war criminals of first priority. Works from CE orcs out for blood vengeance, to LG paladin orders on the quest warpath. Sentient, language-using, cooperating creatures should scare the shit out of you.)

Any potentially memorable NPC that has earned a recurring place in the campaign "graduates" to a 3'x5' index card. I've shown my format for that before. Combat stats rarely come into it because I don't anticipate PCs fighting everything willy nilly. If they do act so stupid, and do so without caution and plausible deniability, the endless hordes come and PCs usually die. Societies may have a range of tolerating community disintegrating nonsense, but there's always a line where they no longer can brook such bullshit.

You're oft safer killing monsters...

Lately I have been using Serif PagePlus Starter Edition to make Savage Worlds cards, print them on cardstock, and sleeve them. Since SW needs less stat space, I can fit them on a card easily. Only a complex card needs to be double sided. I have terrible handwriting though, so printing them out avoids that weakness of mine.

I used to use MS Word during my Earthdawn GMing days, but we had more table space for full NPC sheets (also Earthdawn character stat blocks need that much space usually).