Only your mindset for the experience, also be very careful if you have any family history of schizophenria or other mental illnesses as this can bring them to the for if you have pre-dormant conditions. However that never stopped Swia or boyo. I personally reckon it has a lot to do with the Set and Setting. you must not go into to thinking something bad will happen as this can spiral round in your mind and most likely happen.
Swia would suggest
An environment you feel safe, A person who is trusted that wont take advantage who can help you should u encounter difficulty.
DONT TAKE YOUR CLOTHES OFF and RUN round in blissful happiness if its in your home then by all means. Just dont go sight seeing like SWIA did.
Always remember no matter how difficult things are the experience will end and try not to look at all negative thoughts in a bad way, think why does that go that way, or that was random. the more scared u get of something the more it will magnify