I hesitate to say this, but I don't think it is necessary, depending on what your intention is.
Let's put it this way:
Someone says they have never been drunk, and they are curious about it.
They say, "I was thinking about doing 10 shots of tequila. Will that do it? I want to be sure that I feel the effects."
That's a bad idea. A lot of people that have never drank can feel effects from one or two beers.
With Salvia - don't assume that you won't feel anything, and start out with 20x.
Start out with plain leaf. Get to know Salvia, and how sensitive your are to it. I was surprised that I could feel the effects (about level 3-4) from regular leaf.
If someone says, "I just did 5 shots of tequila, but don't feel anything. I think I'm going to go drive to my friend's house."
Bad idea. Stay put, especially if using the quid method. If you don't feel anything in 45 minutes from the beginning of chewing the quid, chances are, you are safe, but it comes on gradually after 30 minutes.
If someone says, "How can a shot make me feel anything??? I'm going to drink half the bottle." Bad idea. With Salvia, especially 5x and above, you literally need a pinch. If you need more, you can try more, but don't assume you need a lot, because you will be amazed how little you need.
So, do you need a sitter?
I've never used one, but it's a good idea.
If you are going to do it alone no matter what anyone says, remember this:
Start out with regular leaf.
Understand that 5x is = 5 bowls of regular, 20x = 20 bowls, and the usual dosage is 1 bowl.
You will become very uncoordinated, so after inhaling, put down your pipe, bong, etc.
It's best to be on a couch, the floor, your bed, etc., and lie down.
Before you start, learn as much as you can about it at places like
www.sage-wisdom.com
Tell yourself that even if it seems scary, you will be back to "normal" in 10 minutes or so - that the experience is very short lived.
The more you fight it, the more difficult the experience - just breathe through it, go with it.
You will probably forget who you are, how you got there. That's normal.
You may see other people, another reality. It's like dreaming, but being wide awake. That's normal.
The only time I wanted to get up was when I believed that my reality was gone, or that if I didn't get into my reality, it would be gone forever, and another would take it's place, and I would no longer be beanieboy, but someone else, something else, so I would think - I have to get back, I have to get back. It feels like you are in a spirit world, and are trying to get back to this world. So, if you tell yourself over and over before going to Salvia World, that you spirit is tied to your body in this world, and will come back all by itself, you will stop fighting it. Remind yourself to lie still, to be calm, that everything is ok, and it will come back to you should you get scared.
Lastly - it's unnerving. You come back to baseline, and think, "wow, this life feels like a dream. All of those people were real. What is "real"??
And I was nervous to fall asleep later, to return back to that world.
But hopefully, if you have good intentions, you will learn something positive from it.