I might want to get my employees to sign them.

for the best ones, you should consult a local lawyer for one to make sure there is no loop holes. Generally there is a time frame for the NCA like one to two years.

You can also do a search on the web for free templates to get you an idea of what you want. But I definitely also advise taking it to an attorney to look it over.

Enforcing it can be tricky. If these are call center employees and you are trying to stop them from working in a call center within the same industry, I don't think you will get very far. Same with sales etc....

Now, if they developed product X or have an actual vested interest in the company, maybe. But you cannot prevent people from working within the same industry. Stealing customer lists, trade secrets (not obvious items to all hosts) or taking a product built in your company and giving to to company Y, sure. But trying to stop someone at the tech support / sales level from doing tech support at another company, once their business relationship with you is over, is absurd.

Plus, there are very specific laws for making a current employee sign one. It's one thing to have them sign one prior to employment, but after employment it gets a wee bit tricky. Talk to a lawyer, as already suggested.