Self-Defense Training Resources
The Center for Anti-Violence Education (formerly Brooklyn Women's Martial Arts) offers a wide variety of anti-violence programming for women, men, LGBTQ individuals, teens, and survivors of violence. The Center offers self-defense and martial arts courses at reasonable rates, as well as FREE courses for survivors of sexual assault, domestic violence, and child abuse.
For a quick introduction to self-defense techniques, another option is the Rape Aggression Defense System (RAD), which offers 9-12 hour introductory and advanced courses throughout the U.S. and Canada. RAD offers both women-only courses as well as classes for men and kids.
Another option is Impact/Prepare which offers practice on a padded "mugger" in a full force, adrenalized state. This helps the techniques get into muscle memory--like riding a bike--so that a woman always has them when she needs them. For courses outside of NYC, check out Impact Personal Safety.
For intense close combat instruction, Attackproof is an option. Founded by a former police officer and forensic homicide investigator, Attackproof has a much different mission and organizational approach than the above two options, providing training to police officers and military members, as well as self-defense courses for those with no training background. While it is not expressly aimed toward women, it offers serious preparation for real fights, which tend to be dirty, last no more than 30 seconds, and have no rules. The disadvantage to more traditional women's self-defense courses is that they tend to operate under the assumption that you will have a clean punch or kick, which is rarely the case in a real attack. Such courses offer martial arts-based training which assumes that the attacker will behave predictably, which is also rare. Notably, Rape Aggression Defense System (RAD) offers self-defense classes not grounded in martial arts with a feminist approach.
However, you may wish to carefully consider how you will go about learning fighting techniques. Unlike many martial arts that take years to master, Attack Proof will teach you deadly skills very quickly. Because of the habitual thought patterns that may arise in students (anger, fear, anxiety, etc.), most martial art forms teach meditation, while Attack Proof does not. To preserve your peace of mind, you may consider learning how to meditate on your own if you choose to train with Attack Proof or a similar fighting system.