I don't know a lot about gel paint, but I paint Warhammer 40k miniature all the time.
Bright colors usually are a thinner paint while the dark colors are usually thicker.
To get the least watery paint, get a little bit of the paint and let it dry for a while, then you repetitively repaint the same section 2-5 times. This depends on how thick you want it to be. Thicker is better, but takes much longer. Thinner is considered by many modellers to be a sin.
once you are done painting and want to add a bit of "something" to the model, then you should do a thing called dry brush.
Dry brushing is where you get a paintbrush that is dead, beat, overused, ect... Then you dry out some paint dip the old brush into the paint, and you rub the brush as long as you want, as hard a you can, anywhere.
That's how good modelers make this
http://www.dakkadakka.com/gallery/24764-.html And this...
http://www.dakkadakka.com/gallery/22649-Baneblade%20session%20%2301.htmlHope this helps