Be very aware of your surroundings while at a bank (esp. if outside at an ATM). Learn to listen to your instincts - if something/someone in the area doesn't feel right, leave and go to another bank and call LEOs. It is illegal to loiter around a bank - if you see possibly-suspicious parked vehicles within view of banks (even if not in the parking lot) keep a close eye on them, avoid them and CALL LAW ENFORCEMENT. They WILL often roll on a report like that and at the very least investigate. If you can do so without being observed by the suspect(s), get a license number/photo to relay to LEOs. 

When you call LEOs, use 911 and tell them there is a possible bank robbery in progress - otherwise you'll have to be on hold. They will ask you to stay on the line most likely and will want the vehicle make/model, color, license number. That way, if they get a "hit", they will likely mobilize a larger response. As long as there is a reasonable suspicion about the suspect, they will be grateful for the call. 

Bottom line is situational awareness - if you are alert, scanning your surroundings constantly, that alone will likely keep you safe. Criminals tend to focus on the more oblivious among us. If they see someone who seems to be paying attention to their surroundings, they will be more-likely to avoid you. 

Vehicles are not safe. There is a tendency for people to believe that once they are in their vehicle, they will be safe from attack. Unfortunately, one may have one's best escape routes blocked while sitting in a vehicle or have the door yanked open if it's not locked immediately. Even then a person can pull a get-away vehicle in behind your space blocking you from exit, then put a gun in your face and force you to comply ( you should at that point, admit that you have lost the game and cooperate fully). Better to pick a less convenient space to park which offers numerous escape routes or is otherwise difficult for a robber to approach unobserved.

Anyone loitering near an ATM should be reported to LEOs immediately. Don't use an ATM where anyone is loitering within view. Unfortunately people working in businesses or otherwise in locations (bus stops, restaurants, etc) in view of banks can easily work as accomplices to robbers by observing/calling-in likely targets.  If you have to use a walk-up ATM, wait until you are the only person there and turn to face away from the machine while waiting for it to complete functions. If you withdraw a lot of cash, do not turn around so that the cash is visible at any time. Immediately place it into concealment before you turn around so it's not obvious to someone watching you that it was a large amount of cash. 

When using a drive-through ATM, try to select a location where you can easily escape if someone tries to block you in while you are using the machine. 

Even though all this seems unlikely, try to play a game with yourself and think like a criminal when using ATMs or banks. Think about what you might do to rob someone and anticipate their behavior so you can avoid placing yourself into high-risk situations. 

It does not hurt to keep one hand inside a pocket as if you are holding a pistol - remember robbers want money, they DON'T want a fair fight. Easy targets are their only interest so if you appear to be at all alert and prepared to defend yourself, they will pass you by. 

I sometimes set my phone on 911 so all I have to do is hit "send" to connect if something goes sideways. 

Other things to look for around banks are:

- People in the area who are wearing an inappropriate amount of covering of face or body (example, wearing a lot of clothes/hat when air temp is very warm, sunglasses after dark). 

- Signs that someone has been parked in their vehicle near a bank for an extended time (cigarette butts, food wrappers etc,  on ground around vehicle).

- Parked vehicles near banks with illegally tinted windows (so it is not possible to see into the vehicle). Illegal tinting is very common, even though it's illegal, but that doesn't mean to ignore it. Assume the worst, avoid parking around vehicles with illegally-darkened windows and you will be safer. Driving luxury cars as get-away vehicles is increasingly popular with criminals - Rolls, Mercedes, BMW, etc. All are used by criminals because some people think it's less likely the occupants of the vehicle are dangerous. It's not. 

- What appear to be homeless or "crazy" people loitering near a bank. Sometimes they are lookouts. Remember that loitering near a bank is illegal in most places, so if you see it, report it to LEOs or bank security for action. 

- Overly-friendly people or people asking for "help" near banks. This is an increasingly common ploy to get close enough to targets to attack. 

- Vehicles that follow you into a bank parking lot, park nearby or pull in behind you at an ATM drive-through lane. Be prepared to abandon your ATM card if people exit a vehicle behind you for any reason. Have an escape route planned if you get blocked in. Be aware of both the front and back (most drive-though lanes do not have barriers next to them, so you may be able to escape by turning hard right/left driving over a curb and through plants/shrubs). Hit the horn as you do to attract attention. 

NOTE: Follow-home robberies are becoming epidemic in Lost Angeles. If you visit a bank, pay attention to any vehicle that seems to be following. When you arrive at home, get into the habit of always going into the house ASAP, locking the door IMMEDIATELY behind you. A drive-in garage with an auto door that closes behind is great, especially if you have to unload things in multiple trips (take ice cream with you on the first trip). Robbers wait for a target to enter a residence then leave the door unlocked - the robbers barge in through the unlocked door and rob you inside your own residence.