For a first paint-up, it looks really good. Per thinning, there are some great little points in Casey Love's latest SWS video. I'll try to sum them up:
1. He uses clear plastic cups, little wide shallow ones like for dipping sauces, from the grocery store. Using a clear one is key, for later steps.
2. Casey actually blends FWInks with acrylic paints, to make custom colors, which was new to me; I did not realize you could mix the two, but upon reflection they are both acrylic, so it makes sense.
3. After getting the color he wants, Casey adds water until it is quite runny. Here's the tip: he swirls it all together and watches the mixture come off the side of the cup. As he adds water, it obviously thins and as the paint runs down the side of the cup, it become more and more translucent as he adds water. You don't want it completely watered down, but you do want a certain translucency.
4. After it is watered down, he adds 99% alcohol to further thin it and make it flow through the airbrush better. You know you have added too much alcohol because the pigment starts to separate from the solution.
5. Whey applying the paint it can be difficult at times to even be able to tell that paint is being applied until after it has dried. I, too, have noticed that it is better to paint only thin layers and allow it to dry to see the true darkness of the color. I now realize that if I try to make it as dark as I eventually want it as I apply it, it's going to dry too dark. So, the trick is to stop when it is lighter than you ultimately want it to look. Remember, you can always add more layers (Which I prefer, anyway).