In order to get a lot of pigment (which means very intense colors), it is helpful to wet your pans before you start, and to use high quality colors (for example, Schmincke Horadam works very well for me). Sounds weird but the quality of your watercolors is crucial if you'd like to have strong, vivid colors. I also find it easier to get lots of pigment onto the painting if I use a waterbrush. Maybe this helps a bit (although it's kind of late :D).

@@Pfatschke Thanks. It helped me ;)