Most comments for a simple distillation apply to fractional distillation as well.
The distilling pot will need to be heated more vigorously than with a simple distillation, as there is a greater distance for the vapors to travel before reaching the condenser.
|Commonly the column will need to be insulated to maintain heat: wrap the column (and three-way adapter if desired) in glass wool followed by an outer layer of aluminum foil.
|Droplets of liquid should be seen in the fractional column, but there should never be a large pool of liquid (flooding). If the column floods, allow the liquid to drain back into the distilling flask and heat at a gentler rate.