Whatever style(s) you learn, and whoever you learn them from, there are some common points that I don't think anyone with real world experience will argue:
1. Don't M.I.T. it-don't learn so much that you have to select from a large mental catalog of what to do. A few simple techniques well executed will serve better. You need to respond reflexively to a threat.
2. Practice, practice, practice in and out of the formal settings. When I am restraining people who are combative, I ALWAYS grip hands in wristlock fashion whether I am applying one or not. Setup is part of it, the other part is habit building. When I have to grab fast, that is the grip I go for. Same way with breakaways, takedowns, stances, approachs, etc. Try to incorporate it discreetly with how you touch people. That way you develop real world habits. You don't have to use force on everyone you meet, but develop habits of hand and foot placement, stance, etc as much as possible.
3. The element of surprise is critical. Don't advertise skill or style with your mouth, your actions, stance, etc. Where I went what classes I took and what I learned is no one's business. If anybody asks, "I don't know none of that chop suey stuff!". Same rules as concealed carry: Concealed means concealed. I don't know anything about "combat stuff", never had any training, never took a class, just like to shoot old rifles sometimes and punch paper on weekends for fun. That's my story and I'm sticking to it.
4. If you REALLY want to practice weapon retention, try what the boarding parties in the Coast Guard do: Place an airsoft or fake handgun in your holster, get 3 of your friends together in a triangle with you in the middle and have one of them give you a squirt of pepper spray, then keep the gun in the holster for 1 or 2 minutes (time it) while they try to take it away from you. Yeah, I know, you'll be blind, have trouble breathing, in pain. What do you think will happen in the middle of the real world in a surprise attack when you're getting the stuffing kicked out of you and someone spots your weapon.
4. If you think the above is unrealistic remember this: You won't win every fight. There are people out there that are faster, stronger, and have more training than you. And there may be more than one of them. If you don't believe this you watch too much TV.
5. Which leads to another good principle: Learn to run away, learn to stay away, learn to control space and situations and deescalate. Leave the macho at home. It's not about winning it's about survival. Don't run around looking for trouble. Nothing good happens in public after midnight. Bar fights don't happen outside of bars. Put up your antennas and stay out of crowds, alleys, isolated places, and away from liquid courage. Don't be a target, don't be prey, don't be a trophy, don't be a contest. Be the gray man and melt into the wall.