You could stick a wet finger in the air. Or you could use smarter techniques.

1. - Asset Valuation
Value all physical assets
Value all intellectual property
Value all principals and employees
Value all customer contracts

2. - Asset-Replacement-Cost Valuation
Calculate the cost to replace all the assets

3. - The Market Approach
Look at what other similar companies have sold for
Estimate the size and growth potential of your addressable market
Assess the competition and determine the barriers to entry

4. - Income Valuation

5. - Earnings-Multiple Valuation

Read the full story by Martin Zwilling on Forbes.com Sept. 23,  2009