This is highly specific to your particular operations, but here are some basic principles to consider:

Small retail or service businesses probably only need the following:
Commercial Package Policy which includes coverage for:
1. Property
2. General Liability
3. Other miscellaneous as needed. These may include (but is not limited to):
a. Auto
b. Crime
c. Umbrella coverage
Workers Compensation insurance
Employee Benefits Program

More established companies may further want to consider:
Professional Liability (E&O)
Directors and Officers Liability (D&O)
Employment Practices Liability (EPL)
Fiduciary Liability
International coverage

Note: specific industries or operations may require additional types of insurance that are not listed above