My budget is small, so these can save some money and help your soldering skills.

Supplies

Heat shrink tubing

As many alligator clips as you want

Solder and iron

Red and black wire

Hair dryer or heat gun

Multimeter (opt.)

Step 1: Soldering

Put your wire in one clip and turn on your iron. Touch the solder to the tip of your iron and let it drip onto the wire and clip. The end with the wire is the non-clip end, look at the pix to see what I mean.

Step 2: Testing

Take your multimeter and clip one cable on to the leads of your multimeter. Turn it on to the continuity or lowest ohm setting and it should beep or show a very low ohm reading. If you don't have a multimeter, don't worry about this step.