From: United States
Late to the party and what everyone said before is spot on.
The way I have approached things is a little different. In the past as in all things, before I ever designed any scenario I play the game systems for a number of years. This allowed me to get familiar with whatever system it is that I was interested in. Once I figured I had a good handle on that then what I typical do is start to investigate (snoop or spy) on what other scenario designers did and how. So basically this is the poking around stage. Once I got to that point then I would generally find a scenario that interested me and then I'd start by making some basic modifications to it just to see what and how things are possible. At about the same time I look for posts or things in the manual on how to build scenarios to help me out.
Next once I am comfortable with all that, I find a scenario that I'd like to create. Generally, only because this is me, I start with what has others have done before, mainly standing on the shoulders of giants. So for a very basic example lets say I was new to all this and what I would do is look in my board game library and find something small and easy to build. So in this case I (way back when I did this) I picked a game from a company called 3W and the game was entitled East Front Battles I: Blitzkrieg in the South. I choose the first scenario called Scenario 1 - Siege of Kiev, which was a very small introductory scenario.
So the first thing I do is to set the environment variables up for example, basic number of turns, day month year and hex scale.
Now for me what I next did was to create the TOAW map based of a portion of one of the main maps (it came with three) and essentially I mimic the terrain on the paper map to what TOAW had (at that time) and had to do some adjustments to make things fit that the paper map did not have in direct relation to the tools that the TOAW map making editor had. This process takes a while (and this is just copying an existing map by eye/by hand that already has the basic work done, custom maps or ones you create from real satellite images or photos from books can be even more time consuming).
After the map is done what I do is create all the counters (units) in the game, since I generally use a board game as my main reference, generally all the counters are right their to be had. Sometimes you may need to do a little more research to add some chrome, but I'd save that for the last part. I would just get the map done and over with and then make the base units so that you can test to make sure things are not out of whack and feel the way its suppose to feel (i.e., if you are designing an east front game you don't want the Russians in '41 to act and behave like '44 Russians). So for each counter (unit) you create you'll need to find a source for the TOE. There are tons of websites out there for free and there are tons of books that you can purchase. Since you probably know most board war games did a set of some king of calculations to arrive at the combat values for the counters. Sometimes the original designers may have had access to detailed TOE's but most times not, so they would count rifles and guns and tanks and come up with a base number (say 4) and then based on how the unit preformed historically or if they had other sources indicating under/over strength they would adjust from there and then lastly they would adjust for play balance (recall most board war games were designed from 1958 to 1980, from 1980 onward there has not been that much more innovation then since essentially the 1970s. So in some board war games from the early years (AH for example) you would see in D-Day all Allied infantry divisions are showing as 4-4-4 and all armored divisions as 5-5-4 while the Germans are various shapes of 3-4-3, 4-4-3, 5-5-3 for infantry divisions and 1-2-2 for static divisions and 6-6-4 to 3-3-4 for panzer divisions. So just based off that info, you can do some research to find out the TOE's of the various divisions and then fill them in and adjust per above.
Warning note here, if you use the stock db then you can go below, if not you'll need to find or create your own db (TOAW-DB-5.1 is excellent, for pre WW1 there may be some db out there, check Bob Cross's pre-WW1 scenarios).
Once the map and the units are all built up, then you have to make formations, these are the key to playing the game. Also there is more detail that I did not mention such as unit supply, proficiency and readiness. You'll have to set these for the formation as well. There were / are two PDF's that give a good guideline on what to set these to (the one I posted was from the COW or TOAW I) and someone else posted another. Now your ready to set up the Events.
Events is beast in and of it's self and I have run out of time ladies and gentleman.
After the events you have to setup all the PO objectives.
Then you play test it solo. See if it feels right.
Lastly, you add chrome; recolor counters, make documents, scenario briefings, make an image).
I am sure I am missing 30-40% of something or other and details, a lot of trial and error and asking questions when things go south...
hope this helps a little...
War in the East/War in the East II - Alpha Test Teams WarPlan Beta Tester DG CWIE2 tester/SPWW2 and SPMBT playtester/scenario & campaign creator