Drilling glass is VERY tricky business and should not be attempted by a novice, probably will spoil the glass and injure yourself at the same time...
Also, NEVER NEVER drill tempered glass... although a nice hole might go through, tempered glass is not meant to be drilled as drilling it might cause spontaneous shattering later on in it's lifetime or during the drilling process itself..
For ceramics, can try going for lower speeds but still the possibility of cracking is high...