Early on something like 8 Kazaks, 4 Cossack Cavalry and 2-4 Boyar Sons, plus a general and maybe a coupla Druzhina. Then Dvor and more Cossacks as money and technology allows it. Never bothered with Tsars guard. In the end, most field armies were still maybe half Kazaks, but then again, early armies were 2/3 stacks at most anyway.

I used infantry only pretty late (I'm too cheap to field a Dvor army), and then it was an axe line (dismounted Druzhina and/or Boyars, maybe 7-8) with maybe 4 Dismounted Dvor, 2 Cossack Musketeers, 2 Dvor, 3 Cossacks and a General. Sometimes I cycled through old (golden) Boyar Sons and Druzhina, and sometimes it was Basilisks (very seldom in field battles). In any case, missiles did the most part, Dismounted Dvor and Musketeers from the front and Missile Cavalry from the behind. Too much for most enemies' morale to actually engage with the axes... And Dvor can take on almost anyone.