I make a very useful tool in this video. We all use Countersink Drill Bit. It is possible to buy for cheap, but can not we do it ourselves? I wanted to try it and decided to do it. For 4mm drill bit, I started by cutting a 12mm bolt. Then I used a file and gave it the shape I wanted. In the end, something good appeared. I even did the second one, I made for a 3mm drill bit from an 8mm steel bar.
If you want the screw heads to fit properly, you should drill a pilot hole with a Countersink Drill Bit. Whether you buy it or do it yourself, use Countersink Drill Bit. If you want to make it yourself, just watch this video.