How to drill a hole in brick with precision?
The most important part is to start off in the correct location. Once you have started the hole it's relatively easy to keep straight if you take it slowly and have a steady hand.

If your drill has a variable speed - either via a selector switch or by varying the pressure on the trigger - use the lowest speed possible to start the hole. A drill that uses trigger pressure is best as you can start with the drill bit on the mark and then gradually increase the speed. This prevents the bit skidding on the surface.

Once you have the first few millimetres drilled bring the drill up to full speed. You will need to push but don't use your full weight on the drill.

You might find it useful to have someone else watch so they can tell you if you aren't holding the drill perpendicular to the wall.

If you don't have an assistant you can do various things to help you keep the drill level.


Attach a spirit level bubble to your drill at 90 deg to each other. The success of something like this will depend on where you fix the bubble - it has to be parallel to the drill bit and somewhere you can see while drilling.
Use something like this (currently not available for sale) attachement that projects a series of concentric rings on the surface you're drilling into. I've not used anything like this myself, but it looks like it might work.
Buy a drill with built in levels - either bubble levels or electronic.