In my personal opinion right now are these points (the best things to farm):
-Zaishen bounties, Zaishen missions, Zaishen combat and Zaishen vanquish
The bonus with these is you can use any profession and join groups and pug it (people are actually doing these). It is an added bonus if one of these bounties is within a dungeon or a bounty is within a vanquish. Little bonuses like that help with Zaishen coins and gold. For basic builds for professions you can use:
Elementalist: e/mo er prot. This is a ether renewal (elite skill) with a bunch of monk protection enchantment skills. The idea is to enchant yourself with ether renewal, aura of restoration as well as common skills as protective spirit, spirit bond, etc to continually spam the monk skills so long as your ether renewal is up. Search "er prot".
Another ele build is the air spike. Invoke lightning, chain lightning, shock arrow, aura of restoration and air attunement. The others are optionals and a common use are to put fall back and stand your ground/never surrender to support the party.
A last one that could be good is a fire Nuker build. You can use elemental attunement, searing flames, or savannah heat as your elite and bring rogdorts invocation, fireball and liquid flame with your paragon shouts.
Ranger: either a splinter barrage, conditions (if fleshy foes) or interrupts. Splinter barrage build consists of at least splinter weapon and barrage (elite). Pack at max two interupts and maybe throw dirt for melee counter. Bring pve skills like standard of honor or that born shout that boosts attack damage.
The condition build can be anything. I can sometimes get away with using burning arrow with poison tip signet but even better would be apply poison+incendiary arrows. Again bring other interupts and filler skills (support the party/shut down casters or melee).
Lastly for an interrupt build bring broad head arrow and maybe that spirit to make your arrows shoot faster. Fill rest of skills with whatever needed in your party.
Ritualist: are really good farming. But for these Zaishen quests you can load any of the spirit builds that are very popular (sogm, sos or st). Sogm or signet of ghostly might is a communing based build using the elite and a bunch of communing spirits including pain and dissonance and/or whatever you want to throw in the bar. Use armor of unfeeling and 1-2 energy management skills (boon of creation) or the signet/enchant in spawning power for energy management.
Sos is the same concept but in channeling magic. Signet of spirits is your elite and you also bring vampirism (if you have it), bloodsong, painful bond (more useful if you have a sogm person with you) ancestors rage(or)splinter weapon to cast on melee and the channeling skill that steals the spirits energy. Bring pain inverter if you have it.
St or soul twisting is more defensive consisting of skills soul twisting, union, shelter, and the other defensive spirit thats in communing. Cast soul twisting followed by the three spirits, sit back and you got lots of defense. You can even go rt/p and bring stand your ground and other defenses. This build is for hard areas and should NOT be used with a minion master because the minions use up the spirits so they die faster.
Necros: I don't use Necros too much, but most Necros are Heros that run healer builds. The 3-4 skills almost all Necros have now is mend body and soul, (...heal ally for x HP. You lose x HP if there are no spirits in earshot), protective was k. and flesh of my flesh. The other 4 are either in curses with mark of pain, enfeebling blood, pain of disenchantment and signet of lost souls. If in death magic the elite is either aura of the Lich, one minion skill, a hex. Blood magic builds aren't really used as popular.
Dervish: just slap a scythe elite or avatar, bring a bunch of skills that hit high damage, and/or cause conditions and maybe a heal/ress. Dervish builds aren't too formalized as everyone prefers other classes to them (well, I do) so anything works. Remember dervishes are made for crowd control (apply damage, pressure, conditions). Dervishes tend to focus on using only derv skills but some such as wild blow or deaths charge can work as well. Experiment with dervs, they can be fun.
Warriors: I hardly see anything other than 100b all the time. It's useful for triggering mark of pain. For the build search "100b Fowsc" and take out the shadows steps and that's a decent build. If you need to be a tank, use either shadow form and bring a zealous weapon to help with energy or go with defy pain and tank like it's no business. Warriors aren't primarily used as damage or tanks as Ritualist/Necros/mesmers are better damage and assassins are better tanks
Assassin: shroud of distress, shadowform (16 shadow arts with 20% ench mod), unseen fury, deaths charge, iau,... Etc. All assassins do are run tank builds with shadowform. Remember you can maintain it by pre using deadly paradox or glyph of swiftness, you no longer need both.
Or go dagger spammer with jagged strike > fox fangs > death blossom and fill the rest of the bar with a combo. That's the meta chain and add to what you like (support, damage, shutdown...) anything really goes with that build but remember your focus is on damage.
Now that that's all settled you can also power trade which makes good cash.
Vatteirs (shadowform assassin, obsidian armor ele, dagger spammer ranger...)
Raptors (100b warrior + hero)
Speed clears (can do with combination of professions but most common is all assassins)
You can use sos rit to farm uw and fow at least in NM solo. Rare materials drop rate is same in NM/HM
I mean theres bunches of things you can do to farm. I tried to list as many up there; it all boils down to repetitiveness. Ex. Zaishen quests can offer lower returns but isn't as boring while speed clearing can offer high rewards but is monotonous. It's all about preference. Running missions, to and from outposts, quests are generally NOT good ways to make cash unless it's part of the Zaishen of the day. Gwpvx.com has available nicholas of the traveler every week and the gifts sell for 4k apiece and it's a good way to start with money. If you wish to farm materials farm nothing other than jade/amber, granite, feathers, iron, and ectos/obsidian shards. Everything else is already in possession of most players but these materials help with consumable sets and advancing players hall of monuments (which is a MAIN goal for players now) so keep that in mind. HoM = cash. Have a good day!