Several triggers that I have personally experienced in the past, although thankfully I have been cig free for quite some time now:
Alcohol: I don't know if you are a heavy drinker, but if you are, it's going to make it even more difficult to completely quit cigarettes. First of all, all smokers know that alcohol and tobacco have a certain synergy. People who drink also know it can lower your ability to "do the right thing" as it were, you make a stupid choice, smoking a cigarette instead of hitting your PV, in this case. I have a few tobacco flavors that I can tolerate that really help when drinking, chain vaping also helps, as do higher nic and throat hit juices. I absolutely HATE menthol, and once awhile back while drinking with some friends I broke down, and bummed a cigarette from my friend's wife who smokes menthols. It was probably one of the most disgusting cigarettes of my life, so my LAST memory of a cigarette is thankfully not the calm, tasty, relaxing memory most have. It's a memory of a disgusting menthol cigarette. If you have a certain type of cigarettes you hate, and you DO break down, have a nasty one, it will re-train your brain that a cigarette is something that you do not enjoy.
Another trigger was seeing smoking related things. Ash trays, lighters, butts, people smoking, etc. I put away all my ash trays and lighters, and it stopped that feeling you get when you see your empty ashtray on the table staring at you begging to be filled with nasty little butts.
Running out of juice: This happened to be several times in the past. I had run low on juice, didn't think ahead and stock up, and when I ran out I just got a pack of smokes. This was before any of the corner stores were selling disposables so my only choice was to wait days for an online shipment. Now I make sure to have several hundred mils of juice on hand at any time, and frequently restock even if I don't need to. The same goes for equipment, if you run out of good cartos, or all your batteries die, or something along those lines, it's going to be much harder to stay away from a cig.
Drama: Sometimes you can't help but go through things, and then some people seek out drama like it's..... Try to de-stress your life as much as possible. I had a very close friend pass away over a year ago, which caused me to immediately revert back to smoking. Things like this you can't help or change, but in general just try to think ahead and make sure you aren't setting yourself up for something that will cause you to crave a cigarette.
Having cigarettes available: I used to have a pack of cigs stashed away "just in case" this just enabled me to cheat even more. In this case thinking ahead is a bad idea, either finish off all your cigs, or throw them out, either way do everything possible within reason to restrict the availability of cigarettes to you. I do however keep a can of dip around. I was never a dipper in the past, although I did dip on occasion. If you are having a really bad time, and can't stop thinking about a cigarette, a quick dip instead of a cig could help. I know this isn't the most ideal choice, but smoking a cig would be more likely to get you back in the habit of smoking then a dip would. But dip also gives you more of the tobacco feeling you get from real cigarettes compared to ecigs. This has helped me personally, but your mileage may vary.
Don't get super full: I'm sure most smokers are the same in that they would always look forward to that "after a big meal smoke" I noticed (specifically after thanksgiving dinner) that being so full triggered my desire for a cigarette. Whenever you tie smoking into another activity, it makes it harder to stop smoking when you do that activity. Even sex comes into this as well, a cigarette right after, so now that's another trigger. Staying away from sex would probably do more harm then good in reducing your stress levels, not to mention be no fun, but just being aware of these triggers does a great deal to reduce the chance of giving into them, again just my opinion.
I'm sure there's more, but this is all I can think of right now. I like your approach, thinking ahead instead of dealing with the issues as they arise. Good luck to you my friend.