Keeping the drill bit cool is easy

Horizontal drilling for tiles NOT already fitted to the wall

The best overall method to drill material is with a fixed bench drill using a steady trickle of water.

By drilling outdoors you can attach a standard hosepipe behind the drill and fixed with tape to the pillar. Regulate the water flow so you get a steady stream

If you are not able to get to a hosepipe then a watering can, sponge, aspirator, cup or whatever is handy can be used. If your tiles are small enough you can immerse them fully into water via a washing up bowl

 

Easy !