While a 3% conversion off of a visit to your site is not outstanding, it isn't unreasonable either. It could depend on a number of different factors.
1. Where is yoru traffic coming from? If it is from an ad (ppc, banner or email) your message could be unclear and the vistors may be expecting a different experience when they visit your site. I would rework any messages that you have out there to see which ones offer the highest conversions rates.
2.Maybe the layout or the UI of your site needs a little makeover to help your visitors navigate it. If you have any analytics (Google offers it for free) installed on your site you can see the pages that your vistors arrive and leave from - this will tell you where (and maybe why) you are losing them. Maybe there are some barriers like shipping or cost information that aren't clear and creating some hesitation. Once you have this information you can rework your page to stem the loss.
3.Ask the clients that do call you what they think of your site and if they have any feedback for you - there is nothing as good as information straight from your client!