The first important thing about dividing decimals is knowing how to write the problem in the first place! For example, when students see the problem $3.16\,\div~\,0.4\,$ they often incorrectly write the problem as $3.16\overline{\big)\,0.4}$

Actually, $3.16\,\div~\,0.4\,=\,0.4\,\overline{\big) \, 3.16 }$

Once the problem is written correctly, the four steps for dividing are:

1. Move the outside decimal all the way to the right

2. Move the inside decimal to the right the same number of places as the outside decimal was moved

3. Raise the inside decimal straight up

4. Divide