I've been using the Vallejo Model Color line for about a year now, and some of the Model Air paints a little less. I found that using them requires a bit of a learning curve, getting the thinning right at first took a little bit of trial and error on my part. But I love them, for me they are a great paint. I always thin the model color for brush painting and air brushing (I use an Iwata CR and Badger Velocity mainly) often brush painting takes four or five coats, but the coats dry very fast ( I tend to use Kens tip of using a hair dryer on low to accelerate the drying time). I've recently started to use the Model Air paints for brush painting in addition to airbrushing. I find they cover really nicely, again with mulpitle coats. Tamiya paints are good also (that and Model Master were my primary paints before switching to the Vallejo paints) - but I've had to thin them for brush painting and airbrush work also.

Advice is good, but more over experiment with the paints until you find one that works for you. There are many brands of paint and many modelers that will say that brand "x" is crappy and brand "y" is the best paint ever. Try them out, and decide which you like.

Good Luck