patrick206
One thing to really be aware of, Vallejo products should be thinned ONLY with their proprietary thinner, or water. Alcohol or other brand thinners with alcohol base, will definately turn the Vallejo into a gummy mess, the airbrush can be cleaned with lacquer thinner or acetone, but you'll be at it for quite a while.
I've been using Createx Airbrush Cleaner to thin Vallejo paints (both ModelAir and ModelColor), it thins out really nicely and seems to stop tip dry a bit as well.
It seems a strange thing to use to thin paint but it really is a good thinner. I've also used it succesfully in Tamiya, Lifecolor, and Xtracolor Acrylic (as a Brit it does my head in when colour is spelt without a 'U'! :-) ) paints and it sprays nice and smooth.
The reason that Vallejo gums up when anything like alcohol is added is that it's a vinyl based paint. I also know this as I experimented with a lot of different potions to thin Vallejo and spent most of my time digging gummed up paint from my AB. Now I've found the Createx AB Cleaner I won't use anything else.