I fought contamination issues quite a big learning how to TIG so now I'm pretty particular about cleaning.
I got a small squeeze bottle I keep with Acetone for cleaning anything I TIG. I buy a gallon can and refill the bottle as needed.
I've got separate SS toothbrush sized wire brushes for aluminum and steel. For aluminum I've got scotchbrite pads that I will douse in acetone and give the weld areas a quick scrub down- front and back.
For steel I will give the weld area a quick zip with a 50grit roloc pad to remove any rust, scale, paint, etc.
I bought a HTP Tungsten sharpener for under $250- and it is just a huge time saver.
http://www.ebay.com/itm/TIG-Welder-T...-/140451757157
I started storing my TIG welder away from the workbench because this was where I would do dirty work and since I was still randomly fighting contamination I figured it couldn't hurt.
The final thing I figured out that has cured 99% of my contamination issues was switching to a smaller cone on the hand piece. The welder came with a 7 and I switched to a 6 that focused the sheilding gas more. I must have been leaving the tungsten out too far and was loosing the sheilding gas. I'm still not a rockstar but the results have markedly more consistent.