1 - is to quote in such a way as to always have a positive odds if possible otherwise SW risks getting lost. (there you side once to the left, once to the right of your reference line)
2- don't do your holidays in the sketch but afterwards like that your leave will always be good in orientation.
See my example with a single room with 2 configurations.
You would have to draw your whole sketch without quotation then put all your rays in it and put a dot in the middle of each portion of the shelves then you can dimension according to your needs.