Hold the wire between your thumb and first finger and the solder between your second and third fingers. There's NO need for a third hand right now, your second and third fingers have plenty enough dexterity to feed the solder onto the heated wire. Try it, it'll help you time and time again if you learn this little trick.
Heat the wire with a clean soldering iron then feed the solder into the wire. Be sure to heat the wire's core first, the multi core wire will wick up the solder, tinning it nicely.
Now trim the excess length off the wire.
Done! These few simple tricks must have saved me dozens of hours over the course of the couple of years since I learned them. Hours saved from having to hunt for wire strippers, from switching between tools, from having to set up wires in helping hands and from having to retin badly tinned wires before soldering them to other components.