Before raising a feminist son, you and your partner need to sit down and discuss your personal feminist beliefs. You both need to be on the same page before you start instilling your ideologies in your child. If you two disagree on something, make sure you settle it before teaching it to your son, or else you will end up confusing him.
Do not associate certain toys and colours with a specific gender while raising your child. Even though you will typically find parents dressing their male babies in blue and giving them a car or truck to play with, while dressing their female babies in pink and getting dolls for them, you should refrain from making such associations. The idea is to try and teach your son that there is no significant difference between the two genders despite their genetic make-up. Do not expect people to be understanding of what you are trying to achieve. Ignore them and keep concentrating on raising a feminist son.
If you are in a heterosexual relationship, become an inspiration for your son by treating your partner as an equal. The responsibility of demonstrating the strength and respect of a woman to your son lies completely on your shoulders.
Show your son cartoons, films and programs that do not portray females as weak and helpless, but instead show them as strong and fearless. Wonder Woman, X-Men, Dead or Alive and Charmed are a few options that you can choose from. Keep in mind that some of the aforementioned titles may contain content that is not considered appropriate for a very young audience.