sorry for answering a straight forward question with so many words but take what you like and leave the rest.
take advantage of
ECF E-Cigarette Coupons - ECF E-cigarette Forum Coupon Codes Directory and try retail me not, etc. look for *upcoming holidays* that most vendors will promote and buy then. try not to pay retail.
keep a *running tab* of what you're spending and when. friend every vendor you can think of on facebook. buy sample packs. find b & m's in your area and sample there so you don't even have to buy sample packs. if you know that you are the type of person that might like to DIY then start slowly because if you try to buy a lot, it adds up but pays off big time. if you don't think you want to fuss with it then don't. if you love carto's they are something you will have to buy over and over. maybe a rba would save money in the long run, it will. if you go to a b & m to sample juice see if they carry an rba or tank that you're interested in. ask them to show you how to make a coil for it then ask if you can try. if ya like it cool. i want a kayfun lite so bad i can taste it, $99. or, i could buy a clone for $30 but practically everyone has a different opinion on clones. if i get confused i let it go for a while. kayfun is very popular but i don't want a clone so i will have to wait. order, with others, what you need direct from China.
f you have to flip a coin on whether to buy vape stuff or pay your power bill or ship your kids to foster homes then you are in deep trouble.

if you suddenly really start spending heavily ask yourself, why now? maybe you were stressed or depressed so you needed to exert some vape mail therapy. next time you're stressed, you know what not to do.
maybe if you see that you're spending way more money on vapes than cigs it might be an excellent time to ask why. a new groovy mechanical comes out and it's functional and a work of art. save for it first. postpone gratification.
i also get in trouble by watching random reviews, esp phil's. he says you don't have to buy everything he reviews but it's still tempting.
you want to know how i screw up? i spend too much time here so i don't come here as often. that new juice vendor just sounds so tempting and when is the new provari coming out because i'll have to get another--i won't. if i don't buy a kayfun then there will be other reviews on an even better rba that is $10 cheaper. you will 'need it' too. just know that when you buy it, it will be the same thing because there are so many things coming out of china that you will never keep up. never fails.
budget your money for living. i bought a provari 3 months after starting vaping. expensive up front but it stopped my spending on mods in it's tracks. but you will want cool drip tips and damn that new tank looks great on your device.
our kin folk back in the day lived thru the great depression and didn't have a pot to piss in but now americans want it all. we make very little in the US but we support china. lastly, do you have a secure job?!! if not, you might want to be happy with what you have. ps..no job is secure.
if you have money in the bank to make this a great hobby, it is, then spend away. but still, don't pay retail. there's is no price protection in this industry. if you drop $200 on a device and it goes on sale for 20% off the next day, a holiday, then they won't give you your money back.
the one thing that has saved me $$$ was finding two all day vapes...why keep looking except now and then.
you will probably save money on medical bills so we can always 'justify' buying more.
if vapers don't do what CASAA suggests, we could lose vaping. write!!