Welcome! Good luck stompifying dem Ork Boyz!
With the paint problem, it sounds like you're adding too much water. Try dipping the tip of the brush in the paint pot and making a small blob on the palette. Then dip the tip of the brush in a cup of water and bring it back to the blob of paint. Mix it together and see what kind of consistency you have. You'll learn to tell how thick your paints are by how they adhere to the palette as you mix it around.
Usually, if the paint stays super opaque and gel-ish, it's too thick. If, instead, the paint pools into drops (sounds like your problem), it's too much water. Try for something just thicker than milk. (milk consistency is good for washes, a shading technique which I won't go into here) . In my style of painting, I need 2-3 thin coats of paint for full coverage when it is mixed perfectly.
It may be confusing now, but have fun and you'll see what I mean as you begin to sink hours into the hobby
Also, try visiting your local
GW store. In my locality, they run tutorials that can put you
way ahead of the learning curve and save you some serious time.
Good luck!