I explore in nullsec (Venal specifically) in a Helios. Since I started yesterday, I have acquired probably 300+ million in loot, not including the BPCs, in about 2-3 hours of work.
My skills are:
Hacking IV
Archaeology IV
Astrometrics IV
Astrometric Rangefinding III
Astrometric Acquisition III
Astrometric Pinpointing II
Covert Ops IV
This is what my Helios looks like:
My thoughts:
1) With the removal of spawns in sites, you can power through them very fast in nothing but a scanning frigate.
2) With my skills, scan time is almost inconsequential. The bulk of my time is spent actually looking for systems with sites and hacking everything inside.
3) Sites are unreliable. That is to say, sometimes you'll find sites right next to your homebase, sometimes you'll have to go 4-5 jumps out. In nullsec and lowsec (the latter more than the former), the more jumps you make, the higher your chance of dying. Fortunately, I don't have to worry about bubble camps as much since my Alliance/Coalition is the dominating force around this area. This will not be true if you're a solo explorer in nullsec or lowsec.
4) Hacking is also unreliable. My chances of success are probably 80%, and I make good profit despite that, but it always hurts to see a can get blown up. In nullsec sites, I only get two chances at most at hacking a site. A bad string of Suppressor or Repair nodes, or multiple Defense/Offense in key locations, will basically be auto-lose. Though you can hack carefully and intelligently, in the end you're at the mercy of the RNG.
5) Collecting loot is a pain. This time it's the UI getting in the way. Sometimes, the cans eject at such an angle that I cannot go through all of them quickly enough and wind up overlooking the lucrative Data cans. This doesn't happen often, but enough that it is a point of frustration.
6) The cans' relative values are inconsistent. Refer to
this list to tell you the value "tiers" of each can. Data cans are obviously the best, but past that it gets murky.
7) Some people have reported success using a cargo scanner to see if a can is worth hacking. I have yet to try this but I may equip a cargo scanner the next time I fly out.
8) Logistics. This is probably the hardest part about exploring in nullsec/lowsec. For the time being, I have 300+ million worth of loot sitting in my hangar where it's safe. However, so long as it's sitting here it's not exactly liquid, and though the market and industry around Venal is pretty good, it's not good enough to sustain a fulltime explorer. I'm 22 jumps from Jita, the nearest hisec hub, and I'm trying to decide if I want to risk taking it myself (Relic loot is very small, Data loot tends to be larger), or find someone else to move it for me. Whether I want to move in batches or all in once. It's pretty intimidating honestly.
TL;DR: Exploration is good money, but it's unreliable and risky.