Naeblis is correct. He is pointing you in the right direction. I also believe in today's world, personal firearms deserve some consideration as well as martial arts.
Most young criminals are already carrying illegitimate weapons. Although the majority of use is against rivals and opponents, it is prudent to prepare for the eventual encounter involving firearms.
There are many styles that train one for "street fighting". The older more traditional martial arts (Karate, Kenpo, Tai-Chi; Tae-Kwon-Do, Kung-Fu) are probably not suited for today's urban environments.
Thanks to the scientific and philosophical innovations of Bruce Lee in the 60's and early 70's, many respected masters and scholars have realized the need to COMBINE the merits of multiple styles and DESIGN a self-defense/fighting system that is customized for your own personal needs; body type; genetics; fitness level; strength level; height; weight; etc.
I suggest you do some research and get some free advice. Along with any style or styles you choose, remember to include a good hearty fitness and strength program. You must be in good cardio-vascular shape to endure any length of physical combat. Also remember to consider investing in some equipment to augment your training at home, in private.
But, the most important point to remember, in order to be capable and confident enough to defend yourself, it is going to require the best methods and techniques assembled from MULTIPLE styles to create a "fighting system" for yourself. Any advice you receive that differs from this may contain a promotional or selfish angle.
If you need more help let me know!