The logical place to start the Kriya path is taking the SRF Lessons. I'm not initiated into SRF, but I've still taken the lessons, and always recommend people start there, even if they do not stick with SRF specifically. The preliminary techniques like Hong Sau and AUM are as good of a place to start as any. There's also a plethora of wonderful info into the metaphysical aspects of both Kriya specifically and Yoga in general to a depth that I have not seen publicly available anywhere else here in the West. This video here on HRV breathing is another great place to start. Learning how to breath properly is the most important thing in Kriya. It is the breathing itself that leads you deep into a state of Pratyahara (withdrawal of the senses, or the no body state). This breathing style is the foundation that first Kriya is built upon. If you can follow this technique and get good at getting into deep Pratyahara consistently, then it will make learning first Kriya super easy. Most beginners mistakes are in not breathing properly. HTH: