Make Money Online

P = R - C

Where:
P = Profit from Web
R = Revenue
C = Costs

R = N x Q x E x V

Where:
N = Number of visitors
Q = Quality of visitors (ie proportion of visitors inclined to perform desired action - buy product, click link...)
E = Effectiveness of site (in encouraging visitors to perform desired action)
V = Value of desired action (how much you get if visitors do it)

Thus goal is to Maximize N, Q, E and V