Citadel Rhinox Hide Base paint is designed to give a smooth, solid reddish brown color over an undercoat and for that reason this will almost always be the first paint you use on a miniature. Shake the reddish brown paint before using (you can make this easier by adding an agitator ball).
The red-brown paint can be a bit thick sometimes and then you just add a few drops of water to your pallet. You really don't need a lot of water. Something to watch out for is to make sure you don't apply too much paint so that you don't start hiding details.
Another important functionality of this reddish-brown paint is that it not only covers the undercoat, but also covers other colors. So if you later miss something about this color, you can easily paint over it with this Rhinox Hide base paint.
The color of Citadel Rhinox Hide (21-22) is similar to: Old Citadel Scorched Brown; Vallejo Game Color Charred Brown (72045); Vallejo Model Color Burnt Umber (70941) 2; Instar Chocolate Brown; Rackham Dirty Leather (20); Reaper Master Muddy Brown (9028); Privateer Press P3 Umbral Umber2; Scale75 Black Leather Matt.