This is the best reason to put a twig in the ground at each end of a row,
run a string between the two, and follow that line when you sow seeds (at
least until you are able to recognize sprouts). Even if a hard rain scatters
some of the seeds, it's unlikely to scatter all of them. The ones near that
straight line are your guide.

For shallow seeds, like carrots, sprinkle the row with builder's sand (or
even kids' play sand) after sowing. It'll help keep the soil from crusting
over, and cushion heavy rainfall. For all seeds close to the surface, get a
misting attachment (Dramm makes a brass one that's perfect), and water with
that instead of other methods which may float the seed all over the place.