This page is for guides on specific builds. It is to give players a sense of what unit combinations work well against other units.
A general guide is to not mix unit types. For example, do not mix foot with land, air, or naval, or any of these types with each other. Also, do not mix sub-types, such as jeeps with tanks, or choppers with jets. These seem to make units for vulnerable to attacks. Exceptions for this is if you are when you are changing your build and do not have many of one type left.