What are you wanting to use this army for?
In general:
Construct your army from the largest units that will support the weapons you want to use.
Don't build the defaults, they don't do anything.
Don't mix defensive with offensive weapons in these units.
Examples:
Put your interceptors/Helis into units of 400 each.
If you think somebody might try to attack you with a navy, you might want to keep a few high quality units that are 50:50 helis/ints
A division of OAAB/MRMBS is useful for eliminating air defenses.
A division of AAB/DMB is useful for blocking OAAB/MRMB
Read the docs, play the war levels and try to understand are going be most effective for different goals. They give you the probabilities for each weapon so you can study that work out what will work best in any given scenario.
Consider cost as well. Sometimes a very effective approach will be so