Important things to know to make a mission
What is the good guys purpose?
Let's look at the BAS addons. Delta Force was created to battle terrorism abroad.
The Rangers were created to be a light quick reaction force capable of deploying on a moments notice. Experts in patrolling and small unit tactics.
Now I know what kind of missions to make.
What island do I use?
Most of the islands that have come out are fictional making you free from responsibility of an unpopular point of view. Your best bet is to check out island reviews in the review section of this website or to download the island to see just what type of environment you are getting.
why people fight?
smuggling across the border, smuggling from city to city, smuggling weapons, smuggling drugs, people rebelling against the government, terrorists, holding people captive, holding cities captive, holding countries captive, killing innocent people based on race, creed, color or religion, refusing to allow refugees to leave a country or city, killing refugees who just want to leave, etc.
Now you have your two sides, your reason for conflict, your island and you're ready to roll.
Tips:
Be creative
Have fun
Do your best
take a break once in awhile
being simple helps, you won't use up all your ideas in one mission
last but not least....
more than one mission helps, people will play with you for hours