method of drawing split level houses

[kiwicad]

can someone please tell me the general methodology that is successful in drawing split level houses.
e.g. for a split level house over 3 levels,
is the best method:
1. draw say lower level on floor 1
2. draw midlle level on floor 2
3. draw upper level on floor 3 ???
OR
1. draw lower/middle level on floor 1
2. draw say upper level on floor 2
then go around each room on floor1 and drop the floor height to make it
the lowest level, while retaining the middle level at floor height (0) D ?

not sure how to handle stairs leading up/down to the split levels???

any ideas would be great!