If you allow a customer to enter their credit card details into your website (even if you are not charging it at that time,) you should have that page, as well as the page that follows, in a secure (encrypted) area.

Your web host will be able to sell you an SSL certificate that is licensed by a company that most web browsers trust, and your web designer will be able to apply it to your website.

Keep in mind that you have varying options when purchasing an SSL certificate, but it is important to keep in mind that even the cheapest certificate will encrypt the data (the important part.) The more you pay, the more features they will have that verify the legitimacy of the company operating that secure page, and the more trustworthy you will appear to your visitors.

Do everything you can to increase your level of trust, and you will have fewer customers abandoning the sales process.