Equipment
It’s very tempting to include every piece of equipment at your disposal, to create an ‘all singing, all dancing’ affair.
Again, the more ‘props’ that you use, the greater chance there is that something could go awry.
In any case, ensure that your friendly lab’ tech’ knows that you will be observed. If you don’t have the luxury of a technician, make sure that you have previously set up your apparatus and tested that it all works. Don’t rely on ‘it was fine last time I used it’. You never know if a kind soul has inadvertently tidied something and lost bits.