OK so it's Union and Neo-Soviets for you, huh? Hopelessly addicted to Earth? Well, Earth girls are easy, so there is SOME benefit to not being tall, or skinny, or blue...
But seriously, the first step has to be to get the Forcebook. Yes, it's $20, but the options that it gives are splendid. Without the Forcebook for either army, none of the following commentay will make ANY sense whatsoever. And since you were foolish enough to ask for an in-depth dissertation on force building, you now have to sit through the longest ever! Clear sign of being from Earth...
. I have played many games with Neo-Soviets, and a few games against them. I have found that the best course of action with them is stripped down units.I haven't ha a shred of luck equipping Rad Troopers with Rad grenades or bayonets, and my Vanguard have NEVER used that rocket launcher effectively. Of course, my Rad Troopers with SMG's were brutal when they got close enough to use them (move 4", then shoot 3 times!). And my Vanguard with nothing but Venger rifes popped a Ares suit pretty quickly, too. I haven't had much luck with Chemgrunts, but I think that's just a lack of numbers; if I get more Chengrunts, they'll be more effective. Mutants and Cyclops and Predators, oh my! Thse guys have only ever accomplished one significant feat, over and over: they soak up HUGE amounts of firepower. Rad Beasts are 22 points and have 3 LIF, they take a while to kill.... If you can, Ursa suits rock with the Gustav cannon. And the little Typhoon crawlers with the big ugly mortar thing are GREAT! Your "indestructable" mutants can act as spotters... hehehe.... And finally, Bio-freaks are a mixed bag. I have had them do really well, and really bad. There seems to be no "magic formula" for them.
As far as Officers and Kommanders are concerned, I have had my Kommanders accomplish zippo in several games. My Officers, while low in the enemy body count game, are quite exceptional in motivating their own troops. Big Rad Trooper squads means extra bodies to execute.... It took me a long time to figure out how to effectively play the Neo-Soviets. It's only been the last few games that I wasn't completely annhilated. Oh wait, the Zykhee DID annihilate me! And that meant the next game my Commies were at -25% points. But even at the lower PV, I still made the comeback and SQUARELY KICKED THE UNION IN THE A#%!!!! Yeah, there were a few scenario rules that helped, but it felt GOOD to finally get a definitive win against the Good Guys.
Which leads us to the Union. I have only ever fought AGAINST the Union, but I have done so with Neo-Soviets, Zykhee, Growlers, and a plethora of Custom Forces. So I feel qualified to say what DOESN'T work for them. Special abilities for Sergeants seem to rarely do an good. Ares suits are good troop busters, but it's a cool show when they go BOOM! Recon squads are cannon fodder, especially if they have big guns. ADT drones are the most annoying thing ever to fight against. Zykhee Lightning tips add colorful effects to Ares explosions. Elite squads are rarely better than Standard squads. Supply Mules are an excellent value for the re-rolls. Ares suits are pretty when they blow up. Special Forces, although often suggested as being an unfair unit, only seem to kill their own PV (this is based on just one experience, in which a 500 point Special Forces squad spent the whole game engaging a 480 point Zykhee squad.) Commanders with that Initiative roll bonus thingy are the best ever. The Lucifer Plasma Cannon can turn an Ares into a crater. Of course, all this has just been my experience against the Union. And your own experience is more important. Learn from your mistakes, grasshopper!
I have a notebook for every army. I have the battle roster for every game I've played with that army within. After the game, I make notes on that roster about what went right and wrong, as well as who wo and what the score was. I also have a section for every unit type, and after every game I write some commentary about how the unit performed. So before I plan a new roster, I look through my notes. I found out my Rocket Launcher and Grenade Launcher upgrades for my Vanguard slowed the squad down and never accomplished much. Yeah, the models are neat, but by leaving them out, the Vanguard has been my new impact unit. It would have never happened without the record keeping. So ultimately, you will have to learn what works for you. The guidelines that myself and others have posted for you are great starting points, but they will eventually give way to how YOU want to run your army.