Red Carpet Method
When issuing taxi instructions, you should use the "Red Carpet Method". Imagine a red carpet rolls out in front of an aircraft. This red carpet keeps rolling out along all the taxiways you have cleared the aircraft along up to the holding point. No other aircraft must roll onto another aircrafts red carpet. As the aircraft taxis along its route, its red carpet rolls up behind it.
When issuing a taxi clearance, you should always put the current atmospheric pressure (QNH) at the end of the clearance. This must be read back by the pilot.