o level pure chemistry practical

hi are there any sources of errors/precautions for chemistry practicals 🥲🥲 if so, pls do share them and how to improve etc. 🙏🏻🙏🏻

i only know like energy change sources of error (eg. heat energy lost to surroundings then improvement would be use a styrofoam cup)

also, if there are anything to look out for or you have some tips or advices to share, pls do so 🙏🏻 thank you