This is perhaps the most basic and important step toward in motivating your employees. There should not be any unjustified demands for the employers. For example, your worker may not mind two to three late sittings in a month, but if you want him/her to make it a routine, then it is a problem.
There are many bosses who just like to sit in and observe their employees and when the time comes for evaluation, they explode with a barrage of complain regarding the performance. This is just plain wrong. If you see any employee committing a mistake or not working properly, tell him/her at the spot. This will not only force the employee to be more careful, but you will be justified to reprimand him if he/she fails to reach the desired level.
Demand excellence, but first set an example
You are absolutely right in demanding the best from your employees, but if you are not competent enough yourself, they will lose motivation pretty quickly. People who are in charge are supposed to lead by example. If they cannot, they should not be in charges at all.