It is really hard to find a trustworthy real estate broker. You should look for these signs to know if they are trustworthy or not:
They have been a Real Estate Broker for a long time.
They have had successful transactions and positive feedbacks from their clients.
They can be easily contacted online and offline.
They should be affiliated with an office or has an office.
They should have in depth knowledge of the real estate industry.
They should cater to your real estate needs as their priority.
They should guide you and not bug you with your transaction.
These are some of the things that you should look for in a real estate broker but they are not limited to these. Your real estate broker should be your friend for your real estate requirements.
Here is a nice read about a real estate broker: http://redev.ph/broker-blogger-as-property-agent-build-long-