Well it depends on how matured your body is. It is all up to the puberty clock. I suppose if you just keep shaving the small, less visable hairs on your face they will grow back darker. That's how it is for legs.
The best way for a 12 year old boy to grow is to eat a well balanced diet with lots of protein and vegetables, and to exercise regularly.
When you hit puberty.
It isn't common for a 12-y.o. to be able to grow a beard but, if you are already shaving at 12, you will get stubble.
Boys typically start to grow facial hair, including a beard, during puberty, which typically occurs between the ages of 12 and 16. The exact age can vary depending on individual genetics and hormonal levels.
When they are Around 12-16 years old
The normal height for a 12-years old girl is between 5'5" and 5'11". It depends because some girls grow up when they are 12 years old and never grow up, but some girls grow up after they are 12 years old more than 6 inches!
Boys can start growing peach fuzz around the age of 11 or 12, though a full need to shave beard does grow till 16 or 15, though latter or earlier is normal, it's a person to person thing, I know people who are in their 20s that can't really grow a full beard and people that have full beards at 12.
Washing and conditioning it and moisturising it
Colin Beard was born on 1941-12-12.
There isn't anything you can do to force your body to grow. It will do it on its own schedule.
Trust me sweetie, your boobs will grow in (: Be patient! .....or eat..a lot
9 year old children, and all children from ages 6-12 tend to grow approximately 2.5 inches a year on average. Of course there are factors that would affect this, such as genetics, nutrition and gender.