Since you do not indicate what type of experiment you might be performing, I cannot give you a complete answer. Beside all the requirements for any experiment, you have to consider the ethics of the experiment with humans or animals.
I searched Google under the key words "experiment ethics humans" to get these possible sources:
http://en.wikipedia.org/wiki/Human_experimentation
http://www.pcrm.org/resch/humres/humanexperiments.html
http://www.rbs2.com/humres.htm
http://wisdomtools.com/poynter/codes.html
I hope this helps. Thanks for asking.
What is needed when experimenting on humans
3 answers
.elmhurst.edu/~chm/vchembook/5900verviewmet.html on June 6, 2011.
that a negative emonrvinent (yelling. depression, darkness) inhibits growth while a positive one (talking to thep plants) helps it. Keep all the variables the same except the emonrvinent. Use a neutral emonrvinent as your middle ground and and study how this may affect the plants.