If I ever get to the point of taking them I will start with a moderate dose preferably with a trusted sitter.
Don't over think this stuff. In my opinion, a first timer would not need a "sitter", unless he consumes more than an eithgth. Once you have settled your dilema of "jump in the pool" or "test the water", knowing that there is only one first time for mushrooms, then you either want to go to about the 2 or 2.5 gram range for a first time or go to 3.5 - then you might consider a sitter, or at the very least taking them with someone you like who has experienced them before.
Mushrooms are peculiar things - on the one hand they are not to be feared and actually should be embraced, they are not really as strong as LSD, on the other, they are far more powerful and in my opinion are the most powerful substance one could possibly get a hold of. I don't think anyone who has not gone to extremes could easily comprehend this.
A little dose is playful energetic and fun. A moderate dose can be euphoric in the extreme, lending you images and experiences you will never forget, or it can turn you on yourself and have you contemplate your history, possibly to advantage, possibly not. A larger dose can do anything at all and it is at this point you may realize that you are in the presence of raw and unimaginable power - far more than even a large dose of LSD.
Remember this is all subjective, and does not account for the simple scientific facts - a dose of psylocibin is measured in milligrams, a dose of mescaline is measured in hundreds of milligrams but a dose of LSD is measured in micrograms. But it is the essence of the effects and the personality of the chemical that makes all the difference.