First, if you want to blow wicked clouds, keep in mind, there's a danger involved.
The biggest vapor comes not from volts, but Watts. most VV/VW devices have their limits on amps used and wattage used. For people to get the biggest "clouds", they usually drip and build their coils themselves. A complete setup usually involves:
1) Mechanical mod
2) A good battery
3) an Ohm meter
4) Wire
5) wick
6) Dripping Atomizer
7) Juice
skimping quality on numbers 1 and 2 can be dangerous. First, you need to get a mechanical mod. The best ones have low voltage drop. Also, good venting holes are a must when it comes to safety. If something goes wrong, you don't want the gasses to build up in the tube and turn itself into a pipe bomb. Just as bad, is to have the venting holes at the top of the mod (Yes, I have seen this). If a battery vents while you're in the middle of vaping, you'll end up with a burned face.
Seocnd, you need to learn ohms law and get a good battery. All coils are essentially shorting out the battery. The lower the resistance from the negative to the positive, the more power is drawn from the battery. This is where it gets dangerous, since most of the biggest clouds come from very low ohms on good batteries. If someone has the wrong battery, or even thinks he has a good one, but ends up with a fake one, then he is at risk from the battery venting which could lead to an exploding battery, or turn your mod into a hot rocket. get familliar with Ohms law calculator, and know what kind of amps you're pulling from the battery.. this is a MUST.
third, get an ohm checker... again, this is a must. No matter how skilled anyone is, an unseen short can cause a vent. Checking your coils on an ohm meter is a must, and only fools would coil without some way of checking the resistance.
fourth, Wire... you'll have to know what gague you're aiming for. This comes from experience, since the wire reacts differently to different amperages. a Thinner wire gets hot faster, but doesn't come in contact with the juice as much. A thicker wire has less resistance and heats/cools slower, but it has more contact with the juice.
fifth is wick...You may not think there's much to say about this, but there is. Most wicks used by drippers, is cotton. Cottonis cheap, but it will burn if it gets dry. I use cotton on all my RDA (Rebuildable Dripping Atomizer). However I use Silica on my RBA (ReBuildable Atomizer) since most of my newer RBAs have tanks and bury the coils out of view. Cotton holds as much, if not more juice than Silica... however, it does not wick the juice tot he coils the same as Silica. What atomizer may determine what kind of wick you use. To throw other types of wicks in the air, there's Hemp, Stainless Steel mesh, cotton yarn, Steel wire, Bamboo, etc... pretty much anything that can safely hold juice could be an option.
Sixth, is the actual atomizer. I mentioned dripping, since that's the only way to get the largest ammount of vapor. Most of the heavy vapors use drippers because they burn through juice faster than a wick can wick it. "normal vapers" need soemthing that can wick so they can use their tanks. But a dripper and a "cloud chaser" will drip, since they are the limiting factor as to how much juice they have on their wicks.
seventh, and last, is the actual juice. Different juices behave differently to heat. most liquids are made from a combination of VG and PG (or one or the other). PG tends to carry flavor better and have more of a throat hit. VG produces huge clouds but produces less throat hit and less flavor. Most videos that "showboat" their mech mod are showing a VG based cloud. What they can't show you on the video, is taste.
How much for a complete setup? Well, it's not cheap to do it safely, and skimping on quality can be a bad thing.... Mech mods can run you about $25. A dripping atomizer can run you $15, GOOD batteries from a reputable place can run approx $8-9 each, and a good charger is needed for those batteries which will run you at least $20.The wire is pretty cheap, and can get it online, but I'll post $10 for a good supply of wire. Cotton wicks, I prefer organic, but theat will run you about $5.
And I'd just like to let you know, you can produce good vapor from a starter kit, or a low end mod. If it's flavor you're out for, then you just may need to change Atomizers. IF it's the visuals of the vapor you're after, I highly and strongly suggest you do a lot of research.