Making a good scenario
In the Military one thing you have to make sure is that the player has a chance. It is no fun for a player to be facing an army of several hundred soldiers in the first yrs of an adventure. Let them build up their strength as well.
One thing I like to do is build up to a military conflict. Have a few small invasions early on and build on the size as your adventure progresses. One good effect for this in your final episode is to have a certain city attack with a small army. Then on the same month of the following year have the same attack. You are slowly putting your player to sleep. The next year has the same army attack at the exact same time but only this time go with a very large invasion. Players tend to see things as recurring. When you attacked the first two years you let the player think it was a weak army. Now the player is not prepared. Remember however; do not ever place the player in a position of not having any chance. This is not what good adventures are all about.
Lastly is your map. A functional map is easy to make. A great map takes time. Spend a few hours refining your terrain. Add trees and rocks. Add water and beaches as well as swamp land. The more realistic a feel you can get in your map, the more pleasure a player will have playing it. I am not saying everyone out there needs to be an artist. The editor is pretty good at making things look great if you take the time needed to make them look great.
Okay I have gone on about the creation of a good scenario for some time now. In closing remember to test and retest your adventure before submitting it to the world. Get other players to test your adventure. Once everyone has a feel for it and you get good reviews from your testers, then ship it out. Also remember not everyone out there plays at the same level as you. Adventures have to be balanced for everyone if you want them to be truly great.