I really, really need a better silver sword: I still have the one I began the game with after 11 hours of gameplay. I crafted a Gven'nel sword but I have to be at level 13 to use it and I'm only at level 6 or 7... I've found a merchant that sells some good swords but I don't have the money for them. I can't even do witcher contracts quest because they're marked for too high levels (starting from level 11 and up to level 33). Also, selling weapons and armor that I don't use anymore is no good, they're worth almost nothing (which is strange, since in the inventory they are worth something, but when I go to a merchant they're worth much, much less)...
Is there a way to make some money in this game?

I got 3k coin. Bought some repairkits, recipes and gwent card. Haven't bought anything else. Some gold has gone to repairs and I have dismantled quite a lot and not even sold everything.

You do know that blacksmith/armorer pays more for weapons and armor than normal traders/merchants? Herbalists pay double for honeycombs.

I'm looting everything I can and adventuring quite slowly on hardest difficulty, checking every imaginable corner of the maps. 60 hrs played already and only lvl 9. :)

I had the same problem at the early phases of the game too. Later on i noticed that the Mainquest (Story) is lacking a lot of finincial rewards in comparison to the sidequests /witcher quest while the Story will let u level up VERY quickly. The best was to make money for me was to just ride froem Missionboard to Missionboard in Velen and do every Witcherquest you find (as long as u can do it with u rcurrent level/gear). Another good tip is to look for Witcher gear. If u come across merchants that sell u Maps for Scavenger hunts (mostly Blacksmiths/Armorsmiths ). Those Witcher-Armors are already available at a very low level (Especiallly the Griffon armor) and are uprgradeable along the games progress, wich makes the, wotrth the Time u spend on finding their schemes. Sadly i cannot tell u where to get all the schemes ic just know that u will get the schemes for the Heavy Witcher Armor form the Smith at Kaer Trolde at Ard Skellig but that a few hours further into the Game regarding ur Level :D Im not quite surte but i think u can get some Scavenger Hunt Treasuremaps form the smith in Oxenfurt near Novigrad.
Good Luck and excuse me for my mediocre written english :D

One way to make decent money early on is to sell honeycombs to the herbalists in White Orchard for 18 a piece. If you pick a lot of flowers, you can sell extras of those too. They may not seem like much at 1 a piece, but picking herbs has no tedious animation, so you get a lot and they add up fast. I've also been selling things I find a lot of, like alchemist powder (6 each, and I had over 100). You get more pelts than you need for crafting, so they are another thing you can sell for money early (inkeepers seem to pay the most for them).

You can get a new silver sword by doing the viper school quest in White Orchard. You might be high enough level to skip that and get the griffin school sword in Velen.

Oh and if u have a decent Gwint deck u can try the Gwint tournament at the Passiflora wich will lead to rdiculous amoounts of gold even if u loose (i dont know what happenes if win, got unlucky with my cards) that way ive gone up to somewhere at about 13000 coins down to 5000 by ubgrading gear and up to 9000 again without selling a single honeycomb (in fact im stuffed to hell with alchemic ingrdients) just by selling swords and armor i found to the right merchants

To add to this, I also had big stacks of herbs but realized at some point, I'm never going to need them because you only have to craft a potion once and you can refill your stacks by meditating. I decided to keep 20 herbs of each type for now and sold the rest.