Serious? What a wide open question? Lots of factors.

Inside or out?
If indoors, how much space?
What strain do you plan to grow? (Indica produces more than Sativa generally)
How tall would you like your plants?
Will you use CO2?
Do you have good climate control? (plants must have constant fresh air to reach max)

Most plants seem to give about an ounce or so indoors. I have had strains that yield 4-6 ozs. and some are supposed to do more.

More specific questions will get you better info. Good Luck.