Colors: Most of mine are black and white. I also have blue, red, green, yellow, orange, brown, gold, silver, purple, teal, clear and some pink ones to make the Mario design. The acrylic ones are all different colors. I even have some where they are black on one side and white on the other.
First I painted the top and bottom of the sheet with spray paint. Use good paint as MDF soaks up paint. So light colors take a lot of paint and cheap paint just does not work. After I painted the top and bottom, I then cut 1" strips either on a band saw or table saw. I then sanded the edges lightly, then stacked them up and painted the long edges. Make sure the paint dries as if you stack them up too early they will stick together. After that, I then set up my chop saw and cut them in 2" lengths. I then stack them up, 10 to 15 per stack. Then spray the ends. There you have painted dominoes. Some colors you might have to spray twice.

Set Up: You should place the dominoes about 1" apart or a domino width apart. That is when they are in a straight line. As you make curves they need to be a little closer together. The closer together they are the faster they fall but I like the idea of one domino width apart. Too far and they don't always fall right. They all need to be straight and not angled as that might make them not hit the other domino. Unless you are making a curve, then that is different. To make a curve I usually make a reference point like a center of a circle and line the center of the domino to the refence point.

To line up the dominoes evenly spacing. I made several jigs. I made them out of 1/8" ply or Luan wood. Dominoes should be about 1" or one domino thick apart in a straight line. I dado out the slots. Just stack the dominoes in each slot. Then slide the jig up to your next domino and slide the jig back. Some dominoes might stick a little in the dado slots, but it is a lot faster then placing them one-by-one.
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I also made curved jigs to stand the dominoes up in a circle to make it smooth and to fall right. I have four different sizes to make four different sizes of circles. Picture below,

Blocker or Stoppers: These are blocks or stoppers. I use them to stop any mishaps. If I accidentally knock down a few dominoes then they will fall until it hits the stop. The first picture shows two stops. One on the left and one on the right. The second picture shows that when the dominoes fell it stopped at the blocker and the rest stayed up. I suggest using them about every 20 to 30 dominoes or every major group or section. I have lots and lots of these but probably not enough. The other way is to take out about two dominoes and lay them flat where they belong. Just remember to pull out all blockers and stand up any laying down dominoes before you start your topple.

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Cross Over: To cross over a line of dominoes which has already fallen, you need to have a domino that is about 1 & 1/2 times longer so when it is knocked down, it will reach over the fallen dominoes to the other side. The picture below shows how after they have fallen, they reach across the first fallen ones.

Stunts, Tricks and Tips: The imagination can do wonders when using it with a domino topple event. Please check out the stunt pages for more ideas. You can use objects such as soda cans, light bulbs, Legos, Erector Sets, Hotwheel cars, toilet paper rolls, you name it. You don't have to use just dominoes either. I had a idea of using old 3" floppy disk. I taped 3 together so they will stand up. The possisbilites are limitless.