A witcher's main source of income is contracts — small agreements made with paying folk who need some type of monster eradicated or problem dealt with. Geralt, the protagonist of the Witcher 3, is ready and willing to take on many of these contracts.
In Novigrad, the large free city in Velen, Geralt can help out with eight different contracts of varying difficulty. Some of them take him out of the city's limits, but the game considers them to be in Novigrad, so they're included here. This is a difficulty ranking of all eight Novgrad contracts.
8 Deadly Delights
Head to Harborside and check the local notice board, where you'll find a request from the Temple Guard. Apparently, bodies have been found around the area and the Temple Guard wants answers. After doing some investigating, you'll learn that Salma, a succubus, is behind the killings.
You'll have the choice to hear her out and avoid violence, or you can kill her. If you spare her, you'll receive a sword as a reward; if you don't, you can loot her body for a Succubus mutagen.
This quest is fairly straightforward and can be completed without any combat, making it the easiest on the list. Even if you do opt to attack, she isn't that hard to defeat.
7 Doors Slamming Shut
In Hierarch Square or Gildorf's, you can find a notice on the board from Kurt Dysart, a count. He's looking for some help with his house, where doors are slamming shut and walls are shaking. He doesn't think it's a haunting, but something weird is going on. It turns out there are some elven ruins below the property, and within them, an earth elemental is residing.
You'll need to defeat it to help the count. It's a fairly easy quest, although earth elementals have some high defense and require some strategy to take down. It's worth noting that there are wooden supports below the house. If you break them, the house will cave in on the count and he'll die, so maybe try to avoid that.
6 An Elusive Thief
On the notice board in Hierarch Square, Geralt can find a contract offer from Sylvester Amello, a merchant. He says there's an imp causing issues, which Geralt can confirm by using his Witcher Senses. After investigating further, he'll find a doppler that has been living in the city. You'll have to chase him down, with the quest failing if he gets away. After fighting him, you'll be able to spare or kill him.
If you're in the right part of the main Novigrad story, though, you'll have a third option to ask him to help you. This isn't the hardest quest in Novigrad, but it can be difficult to chase him down through the busy city, and the combat against someone with the same abilities as you is sometimes hard.
5 Apiarian Phantom
During one of their conquests through the area, the Wild Hunt lost one of their Hounds, which got separated from its pack. It has since been terrorizing the Honeyfill apiary, and the employees need help.
Once Geralt has investigated and located the Hound, he'll have to take it down. If you immediately kill it, this quest is easy-peasy. However, if it manages to run past you or you don't engage it quickly enough, you'll have to chase it down, which is very annoying and somewhat difficult. It's fast and turns without warning faster than Geralt can.
4 The White Lady
When a young woman dies a tragic death before her wedding day, there's a chance she'll be bound to the earth as a noonwraith — gross, terrifying specters of young maidens in white dresses that hang around farmers' fields at high noon and kill those who approach.
This is exactly what happened to the farmers and peasants outside Farcorners and near Drahim Castle. Through an investigation of these areas or from reading a notice board in Farcorners, Geralt can start this quest. Eventually, he'll find the object binding the noonwraith — a dagger she used to kill herself in life.
Like any wraith, this fight can be difficult. They don't have a corporeal form and really only take any significant amount of damage when trapped with Yrden or under the effects of a Moon Dust bomb.
3 Oxenfurt Drunk
This is one of a few Novigrad contracts that actually takes place mostly near or in Oxenfurt, but the game still registers as a Novigrad quest. Grab a contract from the Oxenfurt notice board posted by the guards. Apparently, the town is being plagued by a mysterious murderer.
This killer turns out to be a vampire, specifically a katakan, who liked preying on drunk men. He prefers alcohol-infused blood, apparently. To lure it out, Geralt needs to get smashed at the local pub. This quest can be hard for a few reasons. Katakans are already difficult foes, but having to do a portion of this quest while drunk is quite the challenge, albeit kind of fun.
2 Creature from the Oxenfurt Forest
While you're in the area of Oxenfurt, you might be able to grab and complete this contract as well. You can find it by reading the notice board, finding Hans, the issuer, at his camp, or by stumbling upon the archgriffin's nest. Hans and his men came to slay the beast but couldn't manage to, and now it's up to you.
You'll need to take down the archgriffin Opinicus, which is no easy feat. These enemies are tough and can be quite the challenge to take down, making this one of the harder contracts in the area.
1 Lord of the Wood
There's a notice on the boards in Farcorners and by Cunny of the Goose looking for someone to help with a problem in the woods. Some dwarven lumberjacks are missing, with only one of their party surviving. This surviving member says he saw a monster, so the local innkeeper who hired them posted the contract.
Geralt can accept this quest and head out to the woods. After some investigation, he'll find a young leshen named Kernun. Destroying its totem summons it to combat, where you'll have to take it down. Leshens are very hard to defeat and are very, very creepy.