Since you have a clear understanding between the difference in Traditional Martial Arts and Reality-Based Self Defense, your quest is to find and enlist yourself in the best RBSD school that you can find in your area.
  Are there any tell-tale signs that you have found a legitimate RBSD school?  You bet there are! The 4 Sure Signs That You Have Found A Good Reality-Based Fighting School: Sure Sign #1 - The Instructor Has A Background As A Body Guard, A Bouncer, An Ex-Convict Or A Military Special Forces Veteran - This instructor may or may not have a high belt rank in some Traditional Martial Art.
  (Ironically, most do, but they usually do not regard it as all that important for what they want to teach you.
) Sure Sign #2 - There Is No Belt Ranking - An RBSD instructor is not concerned with belt ranks as a measure of one's skill.
  What they measure is the skill itself with or without the belt.
  Over the years as the commercial aspect of Traditional Martial Arts evolved, when it migrated to the United States, belt ranking became the standard for rating and keeping a student within a system (while paying monthly dues of course) for years to come.
  Sure Sign #3 - In Reality-Based Self Defense, You Learn How To Fight Quickly - RBSD Schools return to the ancient roots of combat training:  effective, simple, practical and immediately applicable.
  Your curriculum to learn how to fight can be done in a weekend of 1 or 2 days at 8 hours each day.
  After a truly intensive training by a qualified RBSD instructor, it becomes "ingrained in your DNA" - you recall  and remember everything even after many, many months of having trained for the first time.
  Usually only a weekend refresher course is needed, and that can be after 6 or 9 months.
Sure Sign #4 - You Train In Everyday Modern Clothes (Including Shoes) - In RBSD Schools, you will not don a fancy gi, put on a belt or go around bare feet.
  You will train in the same kind of clothes and attire in which you are most likely to fight and you will also be trained in modern-day scenarios, such as in mock alley-ways, stairwells, small rooms with furniture and of course, outside on the concrete.