There are two keys to making proper spun sugar, getting the temperature correct and knowing the correct viscosity to begin spinning.
Essentially you have to get a sizeable quantity of sugar (if you don't have a large enough mass of sugar it will cool down too quickly to be useful for spinning sugar) to the hard crack stage (295-300 F) or beyond to be able to begin to spin sugar. So how do you do it?
If you are doing a clear spun sugar you will want to use a candy thermometer, but if you want an amber spun sugar then your eye will be the only guide you need.
In a deep hot heat about an index finger's worth of sugar and water (add enough water to allow the sugar to dissolve, you can always add more but it'll take longer for it to get to hard crack). Eventually the sugar syrup will be boiling, so let it continue to boil; at this stage you don't want to be shaking, stirring or swirling the pot a lot, that will only encourage crystalization. While the syrup is boiling you will also notice little specks of sugar on the side, some people like to take a wet pastry brush to wipe them away... I prefer to ignore it.
After a while you will notice the syrup getting thicker as it boils, mainly in the way it bubbles. If you want a clear garnish you will need to look at the thermometer now, once it gets close to 295 take the pot off the heat, it'll continue to heat up as you take it off so you never want to take it off when it reaches the actual temperature. If you are making an amber sugar you will notice the syrup start to darken, this is when you can start to gently swirl it to get the syrup evenly coloured. When the syrup reaches a uniform light amber you can take it off the heat. Some people will like to plunge the pot in some water to cool it down, but then again I don't.
Now that you have your pot of scalding hot sugar you'll want to start going to town on it, which is of course the entirely wrong thing to do. If you do it now the streams of sugar will bead up and it won't look right, allow it to cool until the sugar is the consistency of honey and you'll get nice even streaks of sugar.
I assume you prepped your stencils/moulds lined with non stick material (if you're doing shaped pieces of spin sugar) or your two hanging limbo sticks (if you want to do an angel thread bunched sugar look) beforehand so let's start. Using a fork, whisk with the loops cut or simply a handful of wooden skewers dip your utensil generously into the sugar and allow a bit of the excess to drip. Then slowly (if you want a thicker strand) or rapidly (if you want thin threads) wave the dripping syrup over the apparatus. Continue to do so until you get a good coverage at which time allow it to cool before handling. If the syrup gets too thick you can always reheat it a bit more to get it back to a pliable consistency.
That's pretty much it in a nutshell, if I'm not particularly clear on a point just pop a question
"If it's chicken, chicken a la king. If it's fish, fish a la king. If it's turkey, fish a la king." -Bender