lol i just posted a similar post but asking for tips on a particular prac...
firstly you need to ask yourself if it is a quantitative or qualitative experiment before responding your questions, but generally you need to assess four factors in your experiment:
1. RELIABILITY: the key to this is repetition. Take several measurements, repeat the experiment over and over just so that ur result is reliable not a messed up rough one like normal first goes.
2. ACCURACY: How sensative is you equipment? To how many decimals does it take...more the better as the error will be less effective. The condition of your experiemtn such as poor rusting wires will affect it's performance.
3. VALIDITY: this is an assessment of your results where you consider the reliability and accuracy and their impact on your results.
4. IMPROVEMENTS: Do some prior research on some more sensative equipment or other methods that could be used to achieve better results and minimise error.
GOOD LUCK!