Step 1: Find valence e- for all atoms. Add them together.

S=6
F=7x6=42

Total=48

Step2: Find octet e- for each atom and add them together.

S=12*
F=8x6=48

Total=60

Sulfur gets 12 electrons since it should make 6 bonds with surrounding atoms.

Step3: Gives you bonding e-. Subtract step 1 total from step 2

60-48=12e-

Step 4: Find number of bonds by diving the number in step 3 by 2(because each bond is made of 2 e-)

12e-/2= 6 bond pairs

Step 5: Find the number of nonbonding (lone pairs) e-. Subtract step 3 number from step 1.

48-12= 36e-=18 lone pairs

Use information from step 4 and 5 to draw the lewis structure.

Lewis dot structure of SF₆

Alternatively a dot method can be used to draw the lewis structure.
Calculate the total valence electrons in the molecule.
S=6
F=7x6=42

Total=48

Put sulfur in the center and five fluorine atoms on the sides.
Put a pair of electrons connecting the side atom with central atom.Pur remaining electrons on the side atoms.Make sure each side atom get 8 electrons to get octet state.( Sulfur get expanded octet state of 12)