its not too hard, the bulk of hte work invoilved is preping the material to be coated, its very important the part is clean. I usually strip the item of all paint or old powdercoat if I can, then I clean it with acetone, then I prebake the item for 30min-60mins to allow anythign to burn off thats left over, as well as to out gas the metal, if these gasses come out while baking the powder on you can get bubbles. I usually still get a few bubbles on pieces but not too bad, magnesium valve covers are REALLY BAD for this. I hear aluminum is as well but I mainly have the probelm with the valve covers.
The actual coating of the part is easy, my gun is still a cheap gun so I lose as much powder as I get ont he part, its not very effecient, thast where a better gun comes in handy, along with other advantages to a better gun. The gun I want is $1300. Mine is $69. You will need a compressor capable of 12-15 PSI and a dedicated oven to bake in, you can't cook in the oven after you have baked a powdercoated item in it. The temperature is important as well, but a lot of the powders are very forgiving with overbake so I have not had a probelm with that as of yet. Each powder bakes differently at different temps for different times, they tell you what to bake at and for how long when you get the powder.