Tumbling agates: Should you break up whole ones before tumbling? How much should you 'smooth' them?

I've been tumbling some found agates, and I really don't know what I'm doing. Most of the stones are pre-broken fragments, but I've found a couple of whole stones by a riverside. After doing a rough tumble of the whole stones I saw that they didn't show much 'striping', so I broke them open with a hammer and chisel in order to display the patterning. Was this a really bad idea?

Also, the 'rind' of the agates have various degrees of pitting, and it seems that if I rough tumble some of the stones to get rid of all the pitting I'll have very small stones left. Is a little pitting OK, or should I get rid of the pits completely and take the hit on the stone size?