I apologize if this is posted somewhere. One thing I really found myself missing in the rulebook was a basic kind of "Start" here and run this scenario or just take these two characters and do this. I also found that a missing setup section left me wondering if I had really set the game up correctly. So I put it back in the box and decided to ask. What is the best scenario to start with?
For your very first match I would suggest a 1v1 with characters like Wraith, Bunker, Ra, and Omnitron-V. Use Megalopolis, and get things like Line of Sight, Turn order, and how Aim/Dodge/Attack and Defense tokens work.
Note that the game isn't balanced for 1v1, but keeping it simple while you learn the basics of the game is a good idea.
From there move on to a bigger skirmish, 2v2 skirmishes are much more balanced, 3v3 are the best; or try a scenario.
Scenarios are almost never a straight up fight and involve different strategies than skirmishes, they are more objective based than fight based.
Baron Blade and Omnitron Scenarios are great once you have a pretty good idea what you are doing.