What is the best way to make money?

Steal everything, there is so much stuff lying around. You can take anything without any problems as long as there isn't a guard in sight. Enable your Witcher vision and just loot anything that is highlighted. Most items still only give you small amounts of coin, but you'll find a lot of them and it'll sum up.

Fistfighting pays reasonably well, I could bet 100 crowns and even against high level enemies the fights were pretty easy.

You probably can safely sell certain alchemy ingredients if you have many of them, but I can't absolutely guarantee that you won't need them. But who really needs dozens of drowner brains?

But if you don't have 1000 gold yet, maybe you shouldn't start to sail to Skellige just yet. You'll earn quite a bit of money just by doing side quests and contracts, and looting everything in sight.

I've got a goodN for ya but you've gotta have access to Novigrad. Specifically Hierarch Square In Novigrad. Once ya get there locate the merchant standing near his booth and buy all of his seashells. (He'll have 2 kinds of seashells, get'em all!) After buying him out close the trade by saying farewell and then reopen the trade.. The shell will restock after every 'farewell' so When you're satisfied with the amount you have or when your cash-flow starts getting light head to the Armorer who's shop is just a few steps away.. (need to have some $$ left for next step) Use the Armorer to dismantle all the shells (worth $4 and $8) leaving you with a grip of pearls which are now worth $109 and $142 to the Armorer. Now comes the fast cash!! Sell him as many pearls as he can afford before ending the trade. Now that you have all his money you'll need to meditate for a minimum of 5 days before he'll have another thousand or so to spend on more pearls.. Repeating this method of selling pearls then meditating will stack some serious loot and FAST! Only takes a minute or less to do the whole 'sell then meditate' process which adds another 1,000 or so to your wallet each time.. fastest and easiest way I've come across yet!! Shit, I ended up with 8k going on 10k in a matter of minutes!! Hopefully my lack of sleep hasn't made this explanation too confusing to follow! lol... Enjoy!! Make money money, go shopping!! Take money money, go shopping!!

I found this method online days ago so props to the Og who first posted this!

I had 5k by the time I was level 10. At level 15 I'm sitting on 10k, all from looting enemies and selling excess supplies and gear to the right merchants; though sometimes to whatever merchant just to save time. (I keep 20 of an ingredient and keep most strong alcohol).

I've probably sold 500 or more swords, thinking about it that way I've probably killed more people than any ten men on either side of the war. Lol 500 x 6 (lowball average) = 3000. The little things add up. Some sold around 100 or even 200, and that's not counting armor sales.

I thought the same thing early on because there were a few things I wanted to buy, but then I started finding better gear and crafting better gear so I saved the money. I go for significant upgrades only. Buying armor or weapons for a measly +10 isn't worth it.

If my memory serves me well I believe all of this witcher games have a similar economic system. Poor in the beginning, and no worries from the middle onward if you are frugal or don't blow it unneccessarily.