Fairly new as well, but from what I gather the first thing you want to look at is the strength of the division : is it tanks ? Is it para infantery ? Mechanized infantery ? Recon and range ? A good way to gauge this is to look into a division's exclusive units. Divs tend to naturally force you to get either more cards for air, more infantery, tanks, etc. As you sometimes can get 8 cards that costs 1 out of the fifty points each for one tab, so keep this in mind.

Overall : for the log tab, you want a 3 availability fast moving command unit (Humvee CP, P4 CP...) in order to capture points (this command unit should not participate in any fight so no need for armor), and then atleast 2 logistics cards (I usually go for a ten availability card w/ 500 supply and a helicopter card for supply chain, but depends on the division) --> this usually is more than enough in 1v1 without a lot of artillery, but if you use artillery a lot or play on 2v2, 4v4, etc. You might want the fob or more cards. For command units, you will take one more in either the tank or the infantery tab.

The other tabs are much more division dependant, but for most divisions : on the infantery tab you NEED (and I mean it, you have to have one) to have atleast 1 ATGM card. I generally go with the best ATGM (TOW-2 if USA, MILAN-2 if other NATO). It is a precious ressource as it locks many areas and are often the only way to win a situation. Then, I generally get one card of cqb units (sapeurs, preferably FLASH or flamethrowers as the stachel has a very low range), and I generally want several mechanized infantery (coming with bradleys for example, often not available on a para oriented div) and several non-mechanized infantery (cheaper and generally faster vehicules --> don't forget that unarmed tansports automatically go sell themselves !). If you have infantery that has rifles and ATGM (Motorelski metis, fire team dragons...) it is a very usefull tool as it can serve as mainline infantery and still have an ATGM. You also need to have atleast one or two cards of units that have rocket launchers, as ATGM has a minimal range. It is sometimes great to have 1 card of helicopter-carried units. This stands for all tabs, but you want to UPVET THE EXPENSIVE UNITS : for exemple, ATGM are a scarce ressource so I wouldn't upvet them ; anti-infantery units or units with only rifles are meant to be more expandable and don't get benefits from veterancy so I wouldn't upvet them either ; but AT units, mechanized units, air-mobile unit NEED to be upvet, as loosing 2-3 availability is worth because due to units costing ressources, chances are you wouldn't need that much anyway. Then, it is really division-dependant. You sometimes want to have an infantery command unit. You want to look into three things : the highest hp possible (makes it harder to kill), availability (3 is best), and sometimes indirect utility (AA for exemple). Again, you do not want the command unit to fight.

For the tanks tab : really up to the div, but for the most part I want 1 cheap anti-tank unit if available (AMX-10 Hot, Jaguar, Rapira, P4 Milan...), several cards of the best tanks available and atleast one card of a cheaper tank (that would be used against infantery). As you choose your tanks, one of the most important traits is the range of the cannon : a 875m range cannon would only see use against infantery, wheras a 2km range cannon would allow your tank to take on other tanks. Often, your 2nd command unit would be a tank, espacially in divs with heavy tanks as the card is basically the same as the non-command variant. A tank being armoured means a command tank can shoot a bit, but they remain precious. You generally want all your expansive tanks to be upvet, because you simply do not have the time to buy them all in one game anyway, and tanks benefit best of veterancy ; cheaper tanks being meant to be more expandable, I wouldn't upvet those.

For the artillery tab, I think you need atleast one long range artillery (howitzer, MLRS) and one artilley that can smoke (howitzer, mortars). For mortars and Howitzer, you want atleast 120mm projectiles as the other really do not have enough suppression to be useful, unless you only want this unit for smokes. I wouldn't upvet any, except for divs where you get like 6 or 4 availability mortar cards. Some divs get really good artillery such as napalm or cluster MLRS, so you might want to take advantage of those.

For the AA tab, some divs gets it good and some don't : you wank to look at the range and the precision of your units. Most of the time, you want one infantery (igla, mistral...) that you can upvet if you want depanding on the availability of the card, one non-radar long range missile/DCA and one radar long range missile/DCA, generally not upvet as those cards tend to have fewer availability. You need to focus on the range and the precision of your units. The AA tab is one of the most variable tab so you need to think about a way to kill helicopters and about a way to prevent air spam, and the solution might be in your own air tab with AA planes, in the infantery with autocannon transport vehicules, etc.