Few aspects of LGBTQ health care have the myriad of street myths that the topic of hormones have produced. If you ask ten people for their opinion, you are likely to get 15 responses about the best way to start or continue transition. Unfortunately, the web has a ton of inaccurate and potentially dangerous information, so let's start with the basics and move on from there.
The first point of contention is around where to access information and hormones, i.e. the great Doctor versus Street Hormones debate. Although I am rarely one to say definitively "this is the way to do (fill in blank here)," I will do so in this matter. Do yourself a favor and work with a skilled medical provider for transitioning!
Getting your estrogen/testosterone/blockers from a medical provider who has experience working with trans* communities is a controlled and safe way to transition. You know exactly what you are being prescribed and will also be medically monitored to make sure you are healthy while you transition.
One danger of accessing street ‘mones is that you can never be sure of exactly what is being injected into your body when you buy off the street. The other concern is over using new needles, as some folks who sell street ‘mones have pre-filled needles, which is bad news. The other issue that folks rarely consider is that your medical provider can usually save you a ton of money by doing things through a compounding pharmacy. Instead of buying injections for $10-30 every other week off the street, why not work with a doctor who can write you a 3 month prescription for roughly $50-60? Why pay more on the street for less?
If you are considering transitioning and want to find a provider do some homework first. Most LGBTQ health centers have trans* competent providers and the big trend now is moving towards informed consent for care. This is a positive move in care and means fewer places are still requesting letters from therapists or documented "real life experience for 6-12 months" as mandatory steps prior to starting hormones.
Call ahead to see if/how your local queer health center provides these services and if you are not near a major metropolitan area ask them for recommendations closer to home. Most health centers can provide a list of competent folks in the area and if the health center won't share