Hi Hon,
A lot depends where you are. In general you need a medical referral to access hormones and they should be administered under the supervision of an experienced medic. There are very significant health issues associated with going on HRT, the most severe is probably blood clots which can rapidly lead to death, or worse.
The most common model nowadays is informed consent. In this you will have a few interviews with the gender specialist, one to find out if you have any other problems that need to be tackled, for example, many TG people have some degree of PTSD due to our lives of being bullied etc and it is important to find way to deal with this.
You are then given detailed information about what HRT will do to you physically and mentally, you visit an endocrinologist who starts you off on a dose regime to block T and boost E and monitor you take make sure nothing is going wrong.
In some places there is more involved psychiatric evaluation, which can be a real pain.
The process is well explained in the Standards of Care 7 (SOC7). Available from
www.wpath.org and is also in the wiki section here.
Please don't self medicate, it is dangerous and over the counter pills etc are usually totally useless as far as our needs are concerned and you just waste time and money.