Psychedelics can be extremely useful for gaining access other dimensions. They have been used throughout the world for thousands of years during various rituals and ceremonies. It is very important that you understand the different levels of the psychedelic experience when using these sacred compounds for safety reasons as well as a guide for you to use to reach the desired states that you are aiming for.
A great place to get accurate information for psychedelics and other entheogens is at http://www.erowid.org/
I understand that there are people out there who oppose the use of entheogens during rituals but they do have their place as many cultures from around the world has shown us throughout history. I personally believe that the people who frown upon the use of these substances are a product of government and religious propaganda that wish to limit spiritual freedom.