Here's my quick guide to lots of coin and XP.
For anyone wishing a high level and very rich Geralt before act 3 without modding or editing read on.
Playing with the current patched version the arm wrestlers in Flotsam are bugged.
Finish the arm wrestling quest line in Flotsam and then go back to Big Max in the inn. Big Max is easy to beat and each time you beat him you get 60 coin (not the expected 30 coin) and 10xp. It seems like a little, but once you get the hang of it the turn around is faster than farming monsters and gives much more xp.
Furthermore every time you enter the village outside town you can challenge the (former) champ and get another 200 coin (not the expected 100- check you new total) and 20xp.
Using this method you can reach whatever level, and get however much gold you want..... but there's a better way to get rich and experienced in the next act.
Getting richer: I've only played Roche's path, but in Hensalt's camp beat the arm wrestlers. Now the champ can be challenged for 200 coin/win as much as desired (nil experience though).
Now for experience: You need lots (20-30) of the dancing fire bombs. Head into the mist. The wraiths are deadly (but still killable) before Dethmond (sp?) gives you the amulet, but thats ok they're also 45-75 xp/ kill!
This must be done before Dethmond gives you the amulet!!!!!!
Now keep in mind that it is always 1000xp to get a level and do the math.
You should enter the mist with quen active, potions (wolf, tawny oil and swallow) drank, and the whet stone or spectre oil active.
Once you enter you will be swarmed by melee wraiths and shot at by the crossbow wraiths. 1-3hits without quen will kill you. Look around. Assuming the Fort is South then there is a curving ravine to the West- run there pausing only to stab any archer directly in front of you so they put their cross bows away. Stay close to the curve of the wall to block the archers.
When you first enter the cursed battlefield you may appear to lose life /die without taking any hits- you were hit by crossbow bolts. The bolt hits don't register in your status window and are hard to see in the game window- keep moving and find cover in the ravine- stay close to the wall on your right side when you enter.
In the ravine reactivate quen and get ready for the mob coming around the corner- throw lots of bombs when they are all immolated wait- watch for xp in the status window and when you see it watch out- more wraiths will spawn near you- retreat throw bombs retreat, finish off loners or stragglers with the sword.
Now the hardest part is to escape with your hard won XP. You have two choices continue straight through the ravine and be teleported to the centre of the wraith battlefield again, where you then have to run to the fort exit (easier); or take the "off-ramp path" back to the main battlefield and run to the exit (harder in my opinion).
Not that on returning you cannot save until killing the rotfiends who have re-spawned near the wagon (check your map so you don't run back to the cursed battlefield).
This is a difficult XP farm but rewarding usually with 20-30 bombs can get 1-1.5 levels per trip.
The build I started this with was vigor regen (2), parry (2), arrow red (1), fortitude (1)- (don't hate vigor regen from the training tree- the second level gives 25% regen in combat- easy to miss if you read the description fast)
Then from the swordsman tree: Riposte (1), Guard (1), Tough guy (1 later 2), hardy (1), whirl (1- very important!!!), violence (1 later 2), finesse (2), invincible (2), combat acumen (1 later 2), and whirlwind (2).
Relevant gear was armor of Bann X (with +4 AC from plates) and robust blue meteorite sword with fire and ysdkj rune.
I also had the pyromaniac and experienced abilities.
Anyway I'm sure this will work with other builds- but it will take a little practice and some swearing whichever way you do it.
--------------------
Essentially arm wrestling is the fastest way to earn coin in the game- 1 arm wrestling is about 300% faster than any dice poker game and nets more money and (in act 1) gives XP to boot as well.
You can also win arm wrestling 99% of the time.
The game doubles what you should win while your losses remain the expected amount.
An example to clarify: You have 100 coin. You go to Big Max in Flotsam bet 30 coin and win. Your new coin total will be 160 coin- not the expected 130 coin. If you lose, your new coin total will be 70 coin. You will also have earned 10xp if you win.
The xp may seem little but most minor quests will reward you ~100-200 XP for completion, an amount you can easily earn in less than 30minutes of arm wrestling. Also levels are always 1000xp apart.