[Imp]

On using APCs the main asset is mobility & giving the tanks good eyes by having infantry keep up with them who see far better, ignore infantrys ability to see at your own peril.
As I think Andy said tanks lead but try & get to a place of cover to launch an attack, treeline or whatever. Then the infantry move up first for several reasons.
Cheap if die because somethings on the other side & much harder to see, idealy they are not
They can look for targets & are in a position to spot any units opfiring they missed, makes finding ATGMs etc a lot easier.
They can also check out LOS if the terrain is difficult so your tanks move the absolute minimum knowing they have a shot.
They provide a close defence screen
Only now do you decide if its worth the tanks breaking cover.
Now the decision is stay & finnish the job or move & let the arty fall, having a taxi means you can avoid quite a bit of it & relocate to keep the other player off balance.
Concentrate on taking out his vehicles you can now use your speed to avoid his foot units till ready to engage them with your mobile pillboxs still intact if wish.
If contact is expected there should always be infantry on the ground to provide eyes helping prevent ambush. As your tanks are generaly moving at "combat speed" you can rotate your infantry droping one lot off while the others catch up, they do bounding overwatch to.