5α-Reductase inhibitors like finasteride and dutasteride can slightly increase circulating levels of testosterone by inhibiting its metabolism .  However, these drugs do this via prevention of the conversion of testosterone into its more potent metabolite dihydrotestosterone (DHT), and this results in dramatically reduced circulating levels of DHT (which circulates at much lower relative concentrations).   In addition, local levels of DHT in so-called androgenic (5α-reductase-expressing) tissues are also markedly reduced,   and this can have a strong impact on certain effects of testosterone.   For instance, growth of body and facial hair and penile growth induced by testosterone may be inhibited by 5α-reductase inhibitors, and this could be considered undesirable in the context of, for instance, puberty induction .   On the other hand, 5α-reductase inhibitors may prevent or reduce adverse androgenic side effects of testosterone like scalp hair loss , oily skin , acne , and seborrhea .  In addition to the prevention of testosterone conversion into DHT, 5α-reductase inhibitors also prevent the formation of neurosteroids like 3α-androstanediol from testosterone, and this may have neuropsychiatric consequences in some men. 
The basic ingredients for testosterone are zinc, vitamin D, cholesterol, with selenium and magnesium being present as well. Research suggests that an amino acid called N acetyl cystein can be beneficial to increasing glutathione in the testes which makes for healthier teste function and increased testosterone. Sleep is critical. Excess alchohol or body fat do not compliment testosterone production Exercise in proper amounts has been shown over and over to raise T. Moderate amounts of porn and or masturbation are probably fine, but porn induced erectile dysfunction is real. Erectile dysfunction is not fun, it's crushing. Erectile dysfunction can be caused by many things aside from low T. Man up and see your doctor if all else fails. Garlic and vitamin C together have been helpful for me, for what it's worth.