Do not trust drivers. Ever.
I read comments on the police/emergency reports of collisions and wrecks in my area. It's a good reminder of how many psychopaths are behind the wheel who regard cyclists and pedestrians as less than human, little more than speed bumps. Whenever the injured person is inside a car, the comments are full of thoughts and prayers. When the victim is a pedestrian or cyclist, the comments are full of blame gamers who figure anyone who's out in public and not in a rolling cage deserves whatever happens to them.
Niceholes can be worse than overtly hostile drivers. Niceholes will try to be nice and wave you ahead... while the impatient psychopath behind the nicehole swerves around into the shoulder or bike lane, floors it and clobbers you. When a nicehole insists on waving me ahead and I can see there's a potential for conflict with another vehicle, I'll put both feet down, pretend to check my phone, get off the bike, whatever it takes to make it clear that I'm not taking the bait.
Eye contact means nothing. If anything I assume that when the driver makes eye contact he/she is trying to get better aim to hit me.
Do not assume they will stop at intersections, stop signs or red lights, or yield anywhere, anytime. Sure, most will. It's the exceptions who will kill you. I see it every damn ride, walk and run. Twice within two minutes just on my block during Saturday's run.
Keep your ID, phone and essential keys on your person. Always.
If you're hit by a negligent driver or otherwise crash badly enough to need medical assistance, you may be separated from your bike, especially if you're unconscious. Don't keep your ID, phone or keys on the bike.
If your jersey pocket doesn't have a zipper, button, etc., to retain a slippery phone, tuck a bandana around the phone to retain it. Or a grippy rubber band, etc.
Carry at least a minimalist first aid kit.
Doesn't need to be much. I keep a single serve Mylar packet of electrolyte powder, an antihistamine, a couple of Excedrin and an asthma pill (ephedrine with guaifenesin) in my saddle bags. Takes up less room than a CO2 cartridge. Even my smallest bag will hold these few items. And I've needed them a few times, mostly to give to other people suffering from heat exhaustion and dehydration, wasp stings (Benadryl/diphenhydramine is good for emergencies, but not for routine sinus allergies), asthma attacks, etc. I usually keep a waterproof plastic tube with more stuff in my jersey pocket, but the emergency backup stuff goes in the saddle bag. Replace this stuff occasionally, at least once a year. It'll age quickly in a seat bag.
Carry pepper spray for dogs.
And use it. You'll be doing the dog a favor. It's less likely to chase bikes, pedestrians, etc., after getting a snoutful of hot sauce. The gel is safest and least likely to blow back into your face. Forget the water -- dogs just think it's playing. Don't use homemade stuff like wasp spray or squirt bottles filled with whatever you found in your kitchen. A dog owner who's stupid enough to let their dogs roam around harassing people is probably mean enough to sue you for trying to defend yourself. A lawyer could have fun embellishing the effects of homebrewed sprays. Use a good commercially made pepper spray. Sabre is easy to find, affordable and effective. I've used it once on a charging dog and it worked immediately just as claimed.
Close the door when you leave home.
Were you raised by wolves or what?
Don't be the third cyclist playing a Bluetooth boombox at full volume in a group ride.
And your playlist is terrible anyway.