Wearing gloves thin enough to feel easily what you are doing will keep your hands clean. Basic farm wire is dirty with manufacturing residue.
Begin by determining the height and width you want your item to be. A small practice piece would be a good start. Maybe just a ball or alpahbet letter.

Make a base of wire by beginning with the height and bending the wire back down then up again along the first piece until it is as wide as you need it to be or the shape you desire. This cactus pictured started with the basic shape outlined with one single wire.

As the piece grows in demension, criss-cross the wire and wrap around the basic shape for variety of style. As you can see, the cactus is open network of wire but easily retains a cactus shape. It can become as large a body as you would desire by layering the wire more wraps.

Wire work is fairly easy, it will take some practice to get to the point it feels easy. After the piece is complete decide how you want to mount it. Unless you have made a wire base in the process of the design.
The cactus pictured has a base of lava rock. It is easy to drill a hole in and it is not glued, but drilled just the size for the wire sculpture to fit the hole tightly. A flower pot with some cement or plaster is good for display too. Spray paint the wire colors you like for a less rustic look. Small rocks placed in the cement or plaster before it drys add a natural look.

Know the geographical areas where lightning strikes the most. Central Florida, near Tampa, is the most common place in North America for lightning to strike. Every state or region has an area that is prevalent to lightning. Find the spot closest to you by asking a local expert.

Find a few sandy spots near these lightning sites if the sites are near a beach. Make sure the area is of pure sand and not filled with debris. If the lightning sites are in the mountains, find sites on cleared rocks.

Hammer in a eight to 10 metal rods to the spots you chose in the lightning sites. Space the rods out by three to five feet. You do not have to hammer the metal rods into the ground at any certain depth; just make sure the rods are able to stand independently.

Go back and search your spots after a lightning storm. The metal rods should have attracted the lightning to strike the sand or rock, and create fulgurites. Fulgurites are hollow tubes that are lined with glass and resemble the lightning strike.

Extract the fulgurites from the earth. To remove a fulgurite from sand is very easy. Dig the sand away that is around the glass sculpture and lift it out of the sand. A fulgurite is not extremely fragile or brittle but it is made of glass, so use some caution. To extract a fulgurite from rock can be a little more challenging to chisel the rock away from the glass. A hammer and chisel is all that you will need.