As a captain, I try to partner setters and hitters together or two good net players but never two setters together. As for strategy during play, not much different than normal.
If you've played combo before, you probably already know it's a license to sandbag bc there are no DQ's or dynamic ratings during combo. Last fall playing 7.5 my partner and I got handled pretty good in a match, mostly by one guy that had a 5.0 forehand. After the match, my partner said, wow that guy isn't a 4.0 he is more like at 4.5. I said yeah, he was actually the 3.5
the weaker player was the 4.0.