Durring the drill is the heat, so should have the water any time and to reduce the temperature in the drilling will be able to extend the life of the cylinder.
Should be tilted 45 degrees to holes after that cut as normal with 90 degree angles for prevent struggling to get the center.
Should be make sure the material in the right place as you star drill, apply the right amount of pressure during drilling gradually feeding the drill into the material.
Should select the size of electroplated diamond drill, size larger than the size of the hole to be drilled slightly.
The life of diamond drill depends upon the hardness, abrasiveness and thickness of the material being drilled and the specific drilling techniques used.
If after using, diamonds are brown or black around the tip, that is hot in a too high or use a speed in the high, can use water prime lubricant during and will result in the life of the cylinder diamond shorter.
If you want to drill solid materials should use low speed, it will prolong the life of the product.