Pharmaceutical feminizing HRT

Generally speaking, most feminizing HRT regimens will include an anti-androgen, to suppress the effects of testosterone on the body, alongside some form of estrogen and potentially some form of progesterone. This is analogous to the treatment of AFAB people suffering from conditions such as PCOS. However if an orchiectomy has been preformed then treatment with an anti-androgen may no longer be necessary, and AFAB people who wish to still be on estrogen but have had a hysterectomy will also need this regimen. Though if ovaries are intact simply stopping testosterone intake can often allow AFAB people to feminize through the usual aromatase pathway. Depending on health condition and the effects you're going for, your needs may vary. This is a collection of a few HRT regimens we've found potentially useful.

Starting Off
Your first order of business is to get bloodwork done. See Blood tests and staying safe for where to order bloodwork and how to interpret it. If you think you ever want biological kids of your own, you should bank sperm before or immediately after starting HRT. You'll become temporarily infertile a month or two into HRT, and permanently infertile around 9 months in on average, I've heard. Going off hormones to bank later is not fun, and dysphoria may be much worse than it was before you started HRT. See Fertility (AMAB) for more info.

Basic Regimen: Anti-androgen + 17β-estradiol
Either Spironolactone or Cyproterone acetate commonly serve as the anti-androgen. They bind to the Androgen Receptor (AR), preventing Testosterone/DHT from activating the receptor, but as an 'antagonist' (although in reality actually weak partial agonists) they don't activate the AR to a significant degree. Estradiol, also known as E2, is one of the body's natural estrogens. It activates the Estrogen receptors.

Resources

 * WPATH Standards of Care contains "diagnostic criteria", medical treatment recommendations, timelines etc.
 * Hormones: a guide for MTFs is a great, human-readable guide on what to expect from hormonal transition.