When picking an insurance agent, find out if they (are):

Sending you an application without qualifying you. If so, how does he know you're buying the right policy?
Available during business hours
Return after hours phone calls, in the morning
Local, preferably in your home town (Laws and coverages vary from state to state).
Knowledgable about several other plans (Don't expect 30 different carriers)
Asking for the details of what you're insuring. You may qualify for one company but not another
Asking about your risk level. He may not be interested in your needs
Reviewing about your claim history or background. Something may cause a company to decline you.
Dealing in their area of expertise. Agents that try to be all things to all people, aren't
Running an application mill. Some agents only focus on volume
Comparing low and high cost plans. Some companies charge higher premiums for less coverage!
Polite and taking several minutes to give you suggestions. Not everything they do makes them money.

Things you can do:

Regardless of if the agent works for one company or is independent, choose one you are comfortable with
Use someone through word of mouth, the tried and true method
Use common sense when applying for a plan. Do not waste time trying to get the insurance company to pay for a claim or damage that has already happened?
Test out a companies customer service. Can you get through to them or get voice mail? Ask an experienced agent which companys are pains to deal with
Call the insurer to verify details about a policy
After you do buy, read your policy completely so that you can cancel during the free look period
Remember that instant quote services may not be giving you your final premium. Some companies have an agent call or visit you to verify the information first. Others might simply raise your premiums or rating if they disagree with the information you entered. More tips...