All males should wear breathable underwear and pants. Spend some time naked to air out your genitals. Don’t use harsh soaps or wash obsessively.
Uncircumcised men should make sure to wash under the foreskin and dry well afterward. Sometimes, uncircumcised guys get yeast overgrowth under the foreskin, causing itching and rash. Washing and drying well can help prevent this. It can help to use a hair dryer on "low" to dry your genitals after a shower.
Using meds to maintain an erection
It is dangerous to have an erection for too long. The medication someone has been given will state when it is necessary to go to the doctor if the erection does not go away. Many people will buy drugs like Viagra over the internet. This is not recommended as you may have health conditions or be on medications that would make using the drug dangerous.
Some m2f trans workers “tuck” to appear more like a woman. To tuck, a person inserts the testicles inside the open sockets of the pelvis and pulls the penis back towards the back applying tape to secure it. A good tight pair of supporting pantyhose will complete the look by holding everything firmly in place. Every apparatus is different so techniques vary. Try a few different approaches to find what works for you.