What everyone else said, plus...
Something that I didn't see anyone point out is that vaping *is* fundamentally different from smoking analogs. When I smoked analogs, I remember that once I lit one, I was pretty much 'committed'. Tobacco was so expensive, it seemed like a waste to not finish it, and they never tasted good if put out & re-lit later. My point is that, as a smoker, we had an internal "nico-stat" that told us when to smoke. We had the length of the cigarette to tell us when to stop. During the course of a day, that nico-stat would spike when we smoked, then slowly drop over time until it bottomed out and we felt the urge to smoke again.
My nico-stat now, as a vaper, is missing those peaks and valleys... it's a constant, low level of nicotine without the spikes. Since I can take one or two drags and not worry about waste, that's exactly what I do. One drag and back in the pocket. When I first started vaping, I think the novelty of it got me vaping more than I should have... and since I never hit the filter, I had no idea when to stop! Remember also, that nicotine is absorbed much more slowly into the bloodstream for us vapers; it'll sneak up on you. Just bear in mind that you're *vaping*, not *smoking*, and that they different in a lot of ways other than just the lack of flame. As time goes on, and you break the old habitual actions of *smoking*, and really become a *vaper*, you'll find your nico-stat evening out and those overdose episodes will be a thing of the past.
I smoked 1.5 PAD of Camels or American Spirits. I started vaping at 24-26mg, and there I've stayed for 7 1/2 months. I've noticed lately, though, that I'm vaping less and less... my juice bottles don't empty out as fast as they used to

Since I mix my own juice, I have total control over the mg of nicotine in it. I think my next few batches will be 23mg.... the ones after that, 22.... and so on, and so on.....