When it comes to online order forms, your sales pitch should be right on the order form. If you have a very long sales pitch, place a big, visible link at near the top of the pitch that points to the order form itself. This way, people who have already made up their minds to buy can jump right to the order form and purchase without hassle. A s for secure ordering, it may cost you a little bit to set up a merchant account, if you don't already have one. I don't claim that checks by email or fax are anywhere near as effective as credit cards, but they're better than nothing at all.
Most people feel much more comfortable with credit cards.
Additionally, checks can bounce. With a credit card swiper or software, you can find out pretty much immediately if it worked. Go with the option that fits your budget. Keep a mailing list of prospects and a mailing list of customers. Special offers, free gifts, and all the typical promotions can be used in these follow-up letters.