Unfortunately, I'm horrible at making units from scratch, despite working on it for over 3 years. However, I think I do a pretty darn good job on working on what others have done.
Attached, you'll see 3 sets of units: The first are edits from a unit created by Benjamin Ball from his 2300Mars scenario (original to left); the second came from the almars scenario, but I don't know who made it; the third are edits of units made by Alberto Berardi. Again, I didn't make, only edit.
Have some constructive criticism? I'd be glad to hear it.