It seems that there are different schools of thought when it comes to building an Army list for playing with little men.
Most common I seem to have encountered in forum threads lately is the
All bases covered or Combined Arms
Meaning you should have Anti-aircraft, Recon, Smoke, something to assault with, something to hurt heavy tanks with and something with high rate of fire for the hordes.
Obviously it's good to have options for dealing with different sorts of enemy, as long as these options are also something that can be used for other purposes when the particular enemy is not around.
F.Ex 17pdr, a gun to shoot cats with, when facing only infantry , it's a rifle gun team, AAA quite often comes in 2-tank platoon so is a liability in itself, recon is bit more resilient but fragile still.
Play to your list's strengths or Concentrated force
This approach means you should only have units that directly support your combat platoons and their mission, as in if you play Panzers, play as many panzers you can, with minimum points into other 'bases', essentials being Recon and AAA, smoke a nice to have, but not a necessity as you're not gonna stand and deliver, but rather be mobile.
And mostly it's about thinking about what you want to achieve with the force in principal, and figuring out which parts you need for that, then seeing the critical tasks, and possibly adding backup for that, giving redundancy.
If you only have one assault-capable unit in your list, or only one high AT unit, breakthrough/flametank unit, guess which unit the opposing infantry player will be gunning for from the start.
Rambling's over.
