I've made a sizeable mess. Help pls

I've only got access to a 220v 60w iron with a 200-450°C temperature dial and 3 interchangeable tips, 60-40 tin-lead wire, and a small tin of what appears to be rosin flux. I had a miniscule budget to begin with, I've gotta make do with these and whatever household items I can find

The project I'm doing is copper wires that I need to solder to an audio port. It's got left, right, and ground pins, arranged in a square configuration, each with holes in them, presumably to loop wire through

Problems I've identified are:

I can't clean my tip properly, so far I've only got a wet sponge, which I knew was a bad idea, but couldn't find or think of alternatives, resulting in tips that turn graphite-grey. So far that's just meant I have to use areas lower and lower down the iron to get anything done. I've already gone through two tips, I'm on my last one

My flux, or maybe just how I use it, might suck. It carbonises, and that only serves to make it harder to tin the wires. So far flux has served for sweet fuck all

I'm using too much solder for every joint. This issue arises mostly from the aforementioned issues, so far my go-to is to melt a blob off the solder wire, drop it onto the copper wire, and sorta rub it around in the hopes that some of it might permeate. And it rarely does permeate, the solder slides off everything it touches like 90% of the time

The copper itself doesn't heat up enough to melt solder onto it. I figured using the aforementioned blob to conduct heat better into it would work, but as I said, it just doesn't want to stick, it forms a sort of mitten around the wire, refusing to make contact. Probably doesn't help that it's a stranded wire with cloth in its core, about the diameter of the tip of a ballpoint pen at best, this cloth also probably contributes to the carbonising

As for other tools. I've jerry-rigged a pencil holder to feed solder wire through one of the holes in its side, I've got one pair of needlenose pliers squeezed with rubber bands that I'm currently using to prop the copper wires upright, I've got a felting needle in a handle that I use to pick apart stubborn strands of copper, a pair of scissors and a pair of smaller shears, a pair of forceps, and that's about it

And no, I can't take my stuff to a professional and have them do it, I can't afford to go anywhere either