I keep having to solder the wires in my leads, and sometimes in the jack socket of the guitar, time and time again. Is it just bad luck, or are there specific things that can cause that?
Or, maybe, do you need certain kind of solder?

Oh man i hate ****ing leads! They break SO ****in easy. And headphones for that matter. In fact everything i own breaks.
If they keep breaking, how are you doing it? It is key to tin the wire and what you are soldering it to. Before even doing that though, put some flux on what the wire is being soldered to. Make use of the eyelets on pots, switches, and jacks too.
what cjrocker said. and also, when you put the leads through the eyelets, bend them so that they stay there even without solder. called a mechanical connection.
Cheers Cjrocker and Cweavr.
I do use flux and tin the wire beforehand, though.
I'll try bending them. Thanks!
gotta watch from bad solder joints. You should know that the solder should never touch the iron unless you are tinning it. Putting solder on the iron, and then using that put onto wires can cause really bad joints.
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Its just a problem with some leads. The cheaper ones with just the metal end usually break faster. Its from the flexing and pulling. As you move around playing they flex many times, and how many times has it been unplugged. Its just something that happens to wire when used this way. Mine go out when the shield braid breaks, and my 20ft lead is getting shorter each time I fix it. Eventually Ill go spend the money on some good ones.