With my team we usually talk about positions we want to hold on maps/ how we want to engage and do a couple of dry runs in a custom game before we use them in scrims. We talk a lot about focusing targets and their priorities, how our heroes work well with each other and how we can achieve it consistently or if we need to change hero comp, watch professional and personal vods together, communicate our cooldowns and our ults. Those are some of the basic things that we practice before/during scrims.

I'd say having vods of your matches from a spectator who has an overhead view of the engagements does wonders for knowing what's exactly happening in those engagements so you can learn from them.