You know you are in good hands, if your realtor put your interest (as a client) above his/her own interest. Even though usually the interest of the real estate agent is aligned with the client, in some cases they may not be.
For example, when a buyer is not feeling comfortable with a purchase, and buyer is already in contract, and buyer wants to cancel the deal. This is not good for the agent, because the agent will not close and earn that commission. But in some cases, cancelling may be in the best interest of the client. The agent should help the client maneuver through the cancellation and find another suitable home for the client.
Hope that helps,
When you, as a client, really don't understand all of the process (until you've actually experienced it) then it may be hard to determine if you have an agent who is properly representing you. With the internet, it's easy to review realtors online by reviewing their answers to questions here on Trulia. Another good way is by getting a referral from someone who has recently been through the experience of buying or selling a home.
But if you are getting a realtor through referral, make sure and ask detailed questions on why they are referring that realtor, what their experience was like, why did they think their realtor was outstanding. In the end, you'll need to go with someone who you trust as an experienced professional.
Good luck Eva!