What I've discovered a while ago and had confirmed by others both in meat space and online: An easy but incredibly strong means of increasing the net amount of positively-perceived trips is to choose one of the following for the first step (however long your substance is on the come up) of the experience

1) A Cappella

2) Drumming, rattling or humming performed by the participants

3) Solo string or low wind instruments (acoustic guitar covers of pop songs work well in my experience because they're familiar yet unobtrusive enough to put people at ease)

A commonality with poorly-planned setting is often that we go full-hog all systems on max all-in on blasting trippy or ambient music, which can contribute to overall negative reactions as the mind just nopes out of there because it's something it considers too challenging/invasive on top of the other stimuli.

It's long been something of a running theme to say that the best thing for acid is fresh fruit and classical music and I thing it may help to build on that.

I know someone who loves being on acid but coming up just messes with her bad. Personally I used to be the same with mdma and shrooms.

We both greatly reduced the apprehension just adjusting this one element to the point even nausea symptoms have greatly lessened or even all but disappeared.