1. Never bought locally through MercadoLivre, the South American branch of eBay
2. NEVER purchased a M@g-lite, all of them were utter wastes of cash and Eneloop manglers
3. Gotten a BLF A6 instead of any 18650 Thrunites, even though the TN12 2014 served me fairly well
3.1. Failed that, never swapped the NW 4000K-ish TN12 that broke on me for a CW one with hidrous green shift
4. Gone to Lumintop for AA lights instead of insisting on the Thrunites, which were all just a ball ache (so much so that I lost my T10 v1 and didn’t miss it at all
5. Waited until 2016 to buy any Convoys, and directly from Simon at that, because Biscotti is to me like wild singletrack is to a mountain biker
5.1. Failed that, gotten a Biscotti driver to swap on my first S2 right away instead of buying a near-exact copy with Biscotti
6. Purchased a decently potent soldering iron that actually melts the solder for more than a split second
Jack Kellar, i disagree with point 2, maglites were the bomb in the 90’s
Start sooner
Lemme expand on my point:
Mag was the brand for utility lights back in incandescent days. So much so that in South America, they are practically a luxury item. Over here, you spend on a Mag as much as a US guy spends on a Surefire. No exaggeration.
Problem is that this price tag remained for the LED line, and local sellers know this. I legit spent the equivalent of 60 dollars (in the exchange rate back in the day) in one 3D and a 2AA Minimag. Both of which failed. Before that I purchased a 2AAA Mini Mag and was disappointed with the total lack of regulation. Then I bought a camo 2AA Mini that actually worked, but the twilcap spring dented the flat ends of my Eneloops to such a degree that I was afraid they would stop working within weeks. Thank goodness that didn’t happen.
ADDENDUM: I started to legitimately collect lights in 2012, and incans were already long outdated by that point.
I still thought i was the bomb in 2012 with my incan Maglite, until my colleage told me those maglights were hopelessly outdated.
That was the start of all trouble. I got a led upgrade which gave me 200 Lm ! After that i found out that newer LED’s existed, and look where i ended up…
Buy more AA and 2xAA lights, because they’re easier to give away to people I wouldn’t trust with li-ion charging.
I would wait, read more, and try not to jump on “deals” which often don’t turn out quite like expected back when it all started… a few (or was it six!) months ago. 
Batteries are one of the big unknowns and after getting a good charger/tester I started returning them to eBay and buying them from better sources. Also knowing WHAT battery a light needs (no a Q30 isn’t the ONLY battery to covet) helps as low drain batteries work GREAT in a lot of lights (and the latest LT1 lantern)… and they CAN be way cheaper by the dozen if you wait and watch for the deals KNOWING what you want BEFORE jumping on a deal.
So more advice is get good “stuff”, but give yourself TIME for a deal to happen. Again, BLF rocks for spotting deals too.
I guess I’m lucky I got into this habit just a few years ago, I read about some older members who have a lot of lights that WERE da’ not too long ago. 
With that said, it’s taken me just over two years to accumulate a few dozen lights, and a good surplus of “parts” for mods.
Several in this post also mention selling unused lights off and I can see that being a smart thing to consider about now. But not wanting to be a local reseller and shipping is stupid expensive lately for we small operators. So maybe I’ll donate them to local concerns like I did my city manager for reading water meters. Thing is, you don’t know you need a higher power light until you GET one.
But over-all I have zero regrets for any light I’ve bought BECAUSE I did check it all out here on BLF before buying. I travel and hunt/fish a lot and have many hunting friends and hosts in several states that I spend time around the fire with. I have gifted many lights to a larger group of hunters and land owners in the several states I hunt in. They make a REALLY thoughtful gift and are a natural fit for where we are at any given moment… the middle of nowhere!
Final thought though… I have spent about 40 hours or so on modding lights (and I’ve had a tech bench since I got my first HealthKit in the 70s). I enjoy modding, although there were some hard lessons when I got started (on the old C8F 18650 hosts which were a challenge that cost me a few drivers, and about 5 tail springs… actually my cat ate one of those driver’s ICs). Anyway, I am observing new lights coming out this year and seeing that for the price, it’s getting to NOT be worth my time modding most lights coming out lately. The latest C8G from Sofirn HAS all the features I USED to have to “build” into a host that cost twice as much when done with a custom driver, sliced domes, tail bypasses, and TIME.
LONG AND SHORT… better lights from a few manufacturers (listening to BLF) are cheaper than they have ever been for the features they have today. And tomorrow… who knows? So that is my excuse to stay topped off with lights anyway 
i would not get any AA alkaline based lights
either CR123A or li ion, period
i would get an FW3A, totally satisfied with that
then a 1xAAA light with levels
that would probably be it
no zoomies
nothing with PWM
no USB charging
nothing by Manker
no Ti
no Cu
Not buying a fenix TK70 as a first light
Not much differently.
I started with Minimags and then bigger Mags, pride’n’joy was the short-lived 3×AAA Mag.
First “real” lights were a pair of Quark 2AA-Xes (at 80bux a pop… ouch), nice UI with the twist-for-turbo, but horribly green. Functionally about on par with the 2×AA Sofirns now, though, at about a fifth of the price or less.
Got into ’501s and ’502s, loved the drop-in concept. Back then, those lights on Amazon were actually quite good. Really good, in fact, at least as far as hardware. CW real Crees, not (yet) LB fakes, certainly not the crappy “lamp beads” you see out in force today on craplights. Also garbage UIs.
Thing is, Fasttech happily sold me all the LEDs and drivers I needed to turn ‘em from sows’ purses into silk ears. EDCed a really nice 1-mode ’502 almost forever, did like 95% of what I needed in a light.
Not many “mistakes” along the way, so can’t really complain. So like I said, I wouldn’t do much any differently.
Addendum, I actually did get decent cells offa Amazon. Real panny-Bs, protected, clocked in right on the money. Later wanted to get some more for me and the gf, wanted protected cells for her, all pix showed protected (sense-strip down the side), but the fine-print said unprotected. Contacted Amazon to maybe exchange ’em for protected, they said keep ’em but they’d refund the price anyway. Hmm, kewl! So gave her my protected ’Bs and I kept the unprotected ones.
Nowadays I wouldn’t try ordering cells offa Amazon except for proprietary brands like EBL. And those (14500s) worked out quite well.
If I were to get into the hobby now with what I know today ? I would probably learn more about the modding aspect in the beginning and then proceed to see the deeper meaning to the question of balance between raw lumens vs high CRI rather than what I’ve become already…… that being the weirdo that walks around at night with a headlamp, floodlight and thrower in both hands whilst wearing a duty belt equipped with smaller lights and batteries….
Aw, c’mon. Gotta have at least one USB charging flashlight! It’s a fall back if you ever have an issue with your charging unit. I don’t bring a charger when I travel—just one flashlight that can recharge cells. So it serves as the “travel charger.” A Skilhunt H03 RC. Also, should have just one Cu flashlight. So pertie.
I never got into zoomies, glad I didn’t, and won’t start either. Something about them feels just so wrong. About the only aspherical lens flashlight I can tolerate is a Surefire Kroma.
The Cometa is quite nice. I only use it full flood anyway. Too many blurs and smears when shining The Bat Signal.
And I’ve used my MH20 at work to charge cells, as long as button-tops. Hell, I’ve even used it to charge 14500s in a pinch, by balling up some Al foil at the end.
I would never have bought anything with a cool white LED. 
Buy a thrower , buy a flooder , buy a charger , buy a dozen of batteries .., ban myself from this forum and never come back to visit it...!
Doing it over, I would have joined BLF sooner. Otherwise no regrets.
THIS.
Plus I would have focused more on EDC lights that can actually be carried, as opposed to huge monsters that weigh a ton when you’re hiking
I have never bought a flashlight on eBay, and although tempting to get 1000lm for $7, when you’re broke and want a light, I know it’s bogus, inflated marketing. I discovered Convoy, Sofirn and never looked back ince I realized you can get an affordable, high quality light for $20 in a C8 that has higher output than a $150 Streamlight or $200 Surefire. Plus, you can mod it. My Quicko soldering iron power unit was up there with the best $25 I’ve spent!
Maglites were the light to get for quite a while if you couldn’t afford a Surefire or Streamlight. I thought the AA MiniMag and AAA Solitaire were quality, not gimmicky lights. My first flashlight was a 2 AA MiniMag and I did a led conversion on it in I think 2000?. It got lost somewhere though. My Dad carried the Magcharger as a Sheriff in the 90’s and it was awesome. I loved playing with it when I could. Nothing could beat it for throw, output, or as a club (besides a 5D Maglite in the last one).
Sometime in the 1990s is when I started. I disagree with the above comments about Maglites — they were never good. They just sucked less than what else was readily available. While I did have some of their AA lights, you always had to carry two of them due to how unreliable the bulbs were. A sparky friend of mine discovered this the hard way, in the middle of a dark attic, in the middle of summer.
My first ‘real’ specialist light was a PALight. The rubber 9 volt light which had a 24/7 continuous glow. I still have all of these and they all still work and are still used. I wish they still made them actually. Great light to give to non-flashlight people as gifts.
I think my biggest regret has been buying anything from major stores and mass-market brands. Invariably, there aren’t any of those which I use today.
I also find that I use my lanterns most often, flashlights less so. A fringe benefit of lanterns is that they don’t advance anywhere near as quickly as flashlights.