froggy8

Wire wool wont do the job but using a file really gets you down to clean metal and the solder should then stick to the tip

for jobs like that i usually tin the wire 1st then trim to length then have a very small blob of solder on the tip , then hold wire in place and touch the tip to wire and contact for about 1/2 - 1 second and thats it done 

What solder are you using? the type with flux added will make the job easier in almost every scenario. 

Looking at your photos, it looks like the soldering iron wasn't hot enough.

The solder not sticking to the iron obviously isn't ideal but you should still be able to make a neat job.  I've soldered many times on wires using only solder and a mini blow torch pen when somewhere with no electric,  not ideal I know but you get my point about the solder not on the iron tip.

Most irons have a copper tip (maybe coated on some) so a careful bit of filing/scaping should be ok.  Maybe the coating has come off of yours hence why the solder won't stick.

Another thought, would you know if that wire is the cheap Chinese stuff?

I've had problems in the past with cheap wire on rc leads and it's because the strands of wire appear to be stainless steel, not copper.  It can be soldered but I always have to mess about until it works.