Put alternating 'empty' frames between those frames already drawn and with brood.
thomas
We are a bit more cautious with the empty frames. We make sure that every frame of brood is next to at least one other frame of brood. So you might have the pattern BBEBBEBBEBBE where B is a frame of brood and E is an empty frame. That reduces the chances of chill brood. Unfortunately, it also means we have to check the hive more frequently to see if more empty frames are needed. This time of year we check once a week.
I would not suggest two empty frames in a row. As the bees are drawing an empty frame they can keep going right through the empty frame next door, resulting in an overly thick piece of comb. If every empty frame is surrounded by brood there is a barrier to over-extension of the newly drawn comb.