I've only begun cold-calling potential prospects to sell health insurance and workers comp, but I haven't gotten as far as getting past the gate keeper. Are there any quick and easy spiels that I can use?

Basically you can't sell something to someone who is not interested. Cold calling is one of THE hardest things to do if you are just starting. There are no magic spiels. It's just basically more calls equal some sales eventually. It depends on how many hours you want to hit your head against a wall before someone buys something from you that counts.

Good product first of all, when you see the gate keeper, get the names of the people that may make the choices, try and get some names prior to walking into the doors.
Look them up on the internet to know who to ask for.

After you get turned out, get the names of who to ask for and call back latter.
If they tell you that you need an apointment, ask for one then.

Try going in before business hours, when girl out front is not there. Go at lunch time, and after working hours, that will get you in easier.

In larger places, if there is a side or back door stop by and ask for who to ask for.

Leave a lot of cards, and do a lot of call backs