It seems like most people get into it from the chaos magick sort of angle, involving new-age meditation practices which are quite different to the Eastern tradition. Highly recommend reading the Psychonaut Field Manual for a deep insight into a really interesting subculture:
I don't think so, there are no external standards to tell you if your Tulpa is valid or otherwise. It is your own. Now, if you're regularly meditating or then thinking without distraction might come easy but don't let that stop you from trying.
