Here is an excerpt from the new TIG Welding Tips webpage:
What to prepare
The first thing you want to do is prepare the area where you are going to do your welding because you want it to be kept free of contamination. This means that you will have to really clean the area to make sure you have no grease, moisture or dust. You will also want to make sure there are no air drafts in this area because this could bring more problems.
The next thing to prepare is the metal that you are going to use for welding. You will need to make sure that the joints are as clean as you can make them and you do this by using a stainless steel wire brush.