[Wiking]

What I usually do is make a shopping list, max out available points (you lose any you don't spend anyways, so its plenty fair I feel), and decide what is indispensable. Ask yourself, what kind of force am I trying to represent? What can I not live without? And most importantly, what will benefit the most from experience during a campaign?

Adding things that do not really benefit from experience or morale gain during a campaign is probably wasted slots and points (trucks, half-tracks, ammo carriers, etc). Armored cars and very light tanks are arguably wasted points if the battles are large enough as they likely will not survive long enough to enjoy their rewards.

Construct the force around either armor or infantry, and then buy assets that will support your style of play. If you are high mobility then self-propelled artillery is desirable that can keep up. If you're playing footslogging infantry, then perhaps StuG's and other CS-tanks are preferable to help you destroy strong-points or repulse enemy attacks. AT guns are debatable in a core: they tend to die fast to mortar fire and sacrifice their experience gain pretty quickly but are also indispensable for taking the combat load off your tanks. Plus you can upgrade them later to tank destroyers.

Just be methodical and remember there's no "wrong" way to do this!