Casual vs ertheric body
 

Should I start with the casual body or the ertheric body first? Some say the esthetic body is dangerous... but it's the first layer... Not sure how they specifically work...

Don't think of it this way.

Instead meditate to cease mental chatter, when you can control your own mind and rest in internal silence, you will see 'smoke rings' most likely in orange or red - these are vortex's - you project into them to go out of body - project with your intention - intend to be inside it and follow it. Set your destination the same way - "Head to the moon". The tunnel will open and pop you out on the moon.
Which body you used is not important, you will naturally travel in whichever one is most appropriate once you see the smoke rings.

In time the rings will start to present in other colors as your third eye develops and opens more.

To think something is dangerous is to have fear. Never have fear when traveling out of body. Few will land you in the lower astral layers. Not a recommended neighborhood. Instead set your frequency very high through loving yourself, life, the Divine and everything else you can find inside you to love. Open your heart chakra. Travel from this frequency of love.

Do not travel when experiencing fearful thoughts. Control your mind, control your thoughts and have a controlled experience.

Thank you very much