Now, to get this started.
Imagine you have a mib_???? in front of you, he's telling you he wants to make a tulpa.
Without looking at the guides or anything, what are the best advices that you could give him?

This is a huge responsibility, don't do anything stupid, don't give up and you'll be fine. It's totally worth it.

Or send them to the FAQ waffles made. That's kinda what I've been doing.

Why would you want to leave out the guides?
That and just reading around forums always seem to be the best ideas.

I'm talking about a small "precious" advice that you could give him, guides/forum aside.

I personally would tell him to love his/her tulpa as a best friend, maybe even more. Non-romantically of course, but attention and love are the things that matters imho.

The best advice I wish I could have had when I was just starting out with a tulpa is to have faith in them, and believe in their actions.
 I noticed a great amount of progress was made when I tried my best to just believe, and not worry about little doubts that pop into my mind every once in a while.

Don't overcomplicate things and make sure to not see it as a chore. The last thing you should do is make your tulpa your project, you're supposed to be friends, it's okay to experiment a little but never forget that your tulpa is a friend you're experimenting with, not a lab rat you're experimenting on.

Be patient, perseverent and consistent. Also

I wish more people would do #2.

I hope she also was from a dream and somehow also was astrally projecting into your mind from another plane?

There's a difference between an imaginary thing I think up now for shits and giggles and a tulpa. Where the line goes, hard to say. I'd say once the tulpa can move and talk on its own and also is able to have different opinions from you. Ones you don't control consciously at least, in case a tulpa is nothing more than an unconscious parrot. That and when you have your tulpa disagree with you and tell why exactly you're being stupid, it's something special I tell you.

First thing's first, don't create a tupper to play out your sexual fantasy. You can do that stuff in your imagination without forcing a potentially sapient being into it. If you like it though and just make a tulpa for some other reason, sure, if the tulpa also likes it then go for it. But it's not the reason why you should make one. That's about the only thing I can say to your first thing.

"It's subjective" is an alright way to say it if you really want to. I didn't really see your answer in this thread as that, "go for it, don't think about it too much" is how I read it as and I don't think it's a very good one. Creating a tupper definitely can help the host, yeah. But that help should never be at the expense of the tulpa because again, moralfag, possibly sapient, blah blah sobstory.

Not sure what the thing about knowing the tulpa's answer is about. I did tons of personality forcing and thought I knew my tupper very well, but in the end, I only really started to know who he really was once he started talking back to me. Even now, I could only really guess how he would answer to something before he does. I might be right often because we are pretty close, but surprises happen, too.

Beautiful rainbow.