Powder for nasal use can be gotten from gentle boiling off of solution. Fill remainder of cup with an acid such as orange juice. As with all anaesthetics, Ketamine will make the patient nauseaous to varying degrees, directly related to dosage. A non-Ketting person is a great help, and will be fun to talk to, and convenient for changing music, etc. Darkness will eliminate some very strange visual experiences.
Music is very powerful.
Warmth can also be important, as although your respiratory system will not be depressed, you may become cold from inactivity. A blanket is a good idea. Dope should be handy for nauseau, and a bucket should be available as a precaution. Vomitting should be rare, but in the case, it is not a good idea to have to travel to the bathroom. You should try to make sure that your co-trippers start when you do, as it is a rapid starting drug.